Add thin wrapper for nxmx_writer.py (dxtbx.any2nexus) (cctbx#735)

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newsfragments/735.feature

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+Add dxtbx.any2nexus, program to convert any file dxtbx can read to a NeXus file.

src/dxtbx/command_line/any2nexus.py

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+from dxtbx.format.nxmx_writer import run
+import sys
+
+if __name__ == "__main__":
+    run(sys.argv[1:])

src/dxtbx/format/nxmx_writer.py

@@ -1,6 +1,4 @@
 """
-Note, scans and gonios not supported here. This writer essentially writes still images
-
 Example to write 10 cbfs to a single NXmx file:
 writer = NXmxWriter("*.cbf")
 writer.write_nxmx("example.h5")