rgl 1.3.12

Minor changes

readSTL() can now read (some) ASCII format STL files.
The configure script has had minor changes, and autoconf
support files have been updated.
uname is no longer used during startup (PR #435
submitted by Jonathon Love).

Background plots did not always appear (issue #421).
Changing the background resulted in an additional background
object instead of replacing the current one.
Colors weren't handled correctly by writePLY() (issue #425).
bbox3d() objects ignored the xlen, ylen and zlen
settings when rendered using rglwidget() (issue #415).
In certain cases, the WebGL vignette started with the
mouse mode set to "selecting".
The rglwidget() function gets a new argument fastTransparency
which makes WebGL mimic the rgl device when drawing transparent
objects. The default value is TRUE unless option
rgl.fastTransparency is set to FALSE.
writeSTL() now writes endsolid, which is required by some apps.