Downgrade Doxygen to 1.9.4 (#110)

Doxygen 1.9.5 can report false positives. 1.9.4 does
not contain this bug.

docs/doxygen/config.doxyfile

@@ -1,4 +1,4 @@
-# Doxyfile 1.9.5
+# Doxyfile 1.9.4
 
 # This file describes the settings to be used by the documentation system
 # doxygen (www.doxygen.org) for a project.
@@ -19,8 +19,7 @@
 # configuration file:
 # doxygen -x [configFile]
 # Use doxygen to compare the used configuration file with the template
-# configuration file without replacing the environment variables or CMake type
-# replacement variables:
+# configuration file without replacing the environment variables:
 # doxygen -x_noenv [configFile]
 
 #---------------------------------------------------------------------------
@@ -606,8 +605,7 @@ INTERNAL_DOCS          = NO
 # Windows (including Cygwin) and MacOS, users should typically set this option
 # to NO, whereas on Linux or other Unix flavors it should typically be set to
 # YES.
-# Possible values are: SYSTEM, NO and YES.
-# The default value is: SYSTEM.
+# The default value is: system dependent.
 
 CASE_SENSE_NAMES       = NO
 
@@ -918,21 +916,10 @@ INPUT                  = ./docs/doxygen \
 # libiconv (or the iconv built into libc) for the transcoding. See the libiconv
 # documentation (see:
 # https://www.gnu.org/software/libiconv/) for the list of possible encodings.
-# See also: INPUT_FILE_ENCODING
 # The default value is: UTF-8.
 
 INPUT_ENCODING         = UTF-8
 
-# This tag can be used to specify the character encoding of the source files
-# that doxygen parses The INPUT_FILE_ENCODING tag can be used to specify
-# character encoding on a per file pattern basis. Doxygen will compare the file
-# name with each pattern and apply the encoding instead of the default
-# INPUT_ENCODING) if there is a match. The character encodings are a list of the
-# form: pattern=encoding (like *.php=ISO-8859-1). See cfg_input_encoding
-# "INPUT_ENCODING" for further information on supported encodings.
-
-INPUT_FILE_ENCODING    =
-
 # If the value of the INPUT tag contains directories, you can use the
 # FILE_PATTERNS tag to specify one or more wildcard patterns (like *.cpp and
 # *.h) to filter out the source-files in the directories.
@@ -1039,11 +1026,6 @@ IMAGE_PATH             = ./docs/plantuml/images
 # code is scanned, but not when the output code is generated. If lines are added
 # or removed, the anchors will not be placed correctly.
 #
-# Note that doxygen will use the data processed and written to standard output
-# for further processing, therefore nothing else, like debug statements or used
-# commands (so in case of a Windows batch file always use @echo OFF), should be
-# written to standard output.
-#
 # Note that for custom extensions or not directly supported extensions you also
 # need to set EXTENSION_MAPPING for the extension otherwise the files are not
 # properly processed by doxygen.
@@ -1085,15 +1067,6 @@ FILTER_SOURCE_PATTERNS =
 
 USE_MDFILE_AS_MAINPAGE =
 
-# The Fortran standard specifies that for fixed formatted Fortran code all
-# characters from position 72 are to be considered as comment. A common
-# extension is to allow longer lines before the automatic comment starts. The
-# setting FORTRAN_COMMENT_AFTER will also make it possible that longer lines can
-# be processed before the automatic comment starts.
-# Minimum value: 7, maximum value: 10000, default value: 72.
-
-FORTRAN_COMMENT_AFTER  = 72
-
 #---------------------------------------------------------------------------
 # Configuration options related to source browsing
 #---------------------------------------------------------------------------
@@ -1288,23 +1261,6 @@ HTML_EXTRA_STYLESHEET  = ./docs/doxygen/style.css
 
 HTML_EXTRA_FILES       =
 
-# The HTML_COLORSTYLE tag can be used to specify if the generated HTML output
-# should be rendered with a dark or light theme. Default setting AUTO_LIGHT
-# enables light output unless the user preference is dark output. Other options
-# are DARK to always use dark mode, LIGHT to always use light mode, AUTO_DARK to
-# default to dark mode unless the user prefers light mode, and TOGGLE to let the
-# user toggle between dark and light mode via a button.
-# Possible values are: LIGHT Always generate light output., DARK Always generate
-# dark output., AUTO_LIGHT Automatically set the mode according to the user
-# preference, use light mode if no preference is set (the default)., AUTO_DARK
-# Automatically set the mode according to the user preference, use dark mode if
-# no preference is set. and TOGGLE Allow to user to switch between light and
-# dark mode via a button..
-# The default value is: AUTO_LIGHT.
-# This tag requires that the tag GENERATE_HTML is set to YES.
-
-HTML_COLORSTYLE        = AUTO_LIGHT
-
 # The HTML_COLORSTYLE_HUE tag controls the color of the HTML output. Doxygen
 # will adjust the colors in the style sheet and background images according to
 # this color. Hue is specified as an angle on a color-wheel, see
@@ -1668,6 +1624,17 @@ HTML_FORMULA_FORMAT    = png
 
 FORMULA_FONTSIZE       = 10
 
+# Use the FORMULA_TRANSPARENT tag to determine whether or not the images
+# generated for formulas are transparent PNGs. Transparent PNGs are not
+# supported properly for IE 6.0, but are supported on all modern browsers.
+#
+# Note that when changing this option you need to delete any form_*.png files in
+# the HTML output directory before the changes have effect.
+# The default value is: YES.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+FORMULA_TRANSPARENT    = YES
+
 # The FORMULA_MACROFILE can contain LaTeX \newcommand and \renewcommand commands
 # to create new LaTeX commands to be used in formulas as building blocks. See
 # the section "Including formulas" for details.
@@ -2383,38 +2350,26 @@ HAVE_DOT               = NO
 
 DOT_NUM_THREADS        = 0
 
-# DOT_COMMON_ATTR is common attributes for nodes, edges and labels of
-# subgraphs. When you want a differently looking font in the dot files that
-# doxygen generates you can specify fontname, fontcolor and fontsize attributes.
-# For details please see <a href=https://graphviz.org/doc/info/attrs.html>Node,
-# Edge and Graph Attributes specification</a> You need to make sure dot is able
-# to find the font, which can be done by putting it in a standard location or by
-# setting the DOTFONTPATH environment variable or by setting DOT_FONTPATH to the
-# directory containing the font. Default graphviz fontsize is 14.
-# The default value is: fontname=Helvetica,fontsize=10.
-# This tag requires that the tag HAVE_DOT is set to YES.
-
-DOT_COMMON_ATTR        = "fontname=Helvetica,fontsize=10"
-
-# DOT_EDGE_ATTR is concatenated with DOT_COMMON_ATTR. For elegant style you can
-# add 'arrowhead=open, arrowtail=open, arrowsize=0.5'. <a
-# href=https://graphviz.org/doc/info/arrows.html>Complete documentation about
-# arrows shapes.</a>
-# The default value is: labelfontname=Helvetica,labelfontsize=10.
+# When you want a differently looking font in the dot files that doxygen
+# generates you can specify the font name using DOT_FONTNAME. You need to make
+# sure dot is able to find the font, which can be done by putting it in a
+# standard location or by setting the DOTFONTPATH environment variable or by
+# setting DOT_FONTPATH to the directory containing the font.
+# The default value is: Helvetica.
 # This tag requires that the tag HAVE_DOT is set to YES.
 
-DOT_EDGE_ATTR          = "labelfontname=Helvetica,labelfontsize=10"
+DOT_FONTNAME           = Helvetica
 
-# DOT_NODE_ATTR is concatenated with DOT_COMMON_ATTR. For view without boxes
-# around nodes set 'shape=plain' or 'shape=plaintext' <a
-# href=https://www.graphviz.org/doc/info/shapes.html>Shapes specification</a>
-# The default value is: shape=box,height=0.2,width=0.4.
+# The DOT_FONTSIZE tag can be used to set the size (in points) of the font of
+# dot graphs.
+# Minimum value: 4, maximum value: 24, default value: 10.
 # This tag requires that the tag HAVE_DOT is set to YES.
 
-DOT_NODE_ATTR          = "shape=box,height=0.2,width=0.4"
+DOT_FONTSIZE           = 10
 
-# You can set the path where dot can find font specified with fontname in
-# DOT_COMMON_ATTR and others dot attributes.
+# By default doxygen will tell dot to use the default font as specified with
+# DOT_FONTNAME. If you specify a different font using DOT_FONTNAME you can set
+# the path where dot can find it using this tag.
 # This tag requires that the tag HAVE_DOT is set to YES.
 
 DOT_FONTPATH           =
@@ -2657,6 +2612,18 @@ DOT_GRAPH_MAX_NODES    = 50
 
 MAX_DOT_GRAPH_DEPTH    = 0
 
+# Set the DOT_TRANSPARENT tag to YES to generate images with a transparent
+# background. This is disabled by default, because dot on Windows does not seem
+# to support this out of the box.
+#
+# Warning: Depending on the platform used, enabling this option may lead to
+# badly anti-aliased labels on the edges of a graph (i.e. they become hard to
+# read).
+# The default value is: NO.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_TRANSPARENT        = NO
+
 # Set the DOT_MULTI_TARGETS tag to YES to allow dot to generate multiple output
 # files in one run (i.e. multiple -o and -T options on the command line). This
 # makes dot run faster, but since only newer versions of dot (>1.8.10) support