Bugfix: Cmd-S on an unmodified document inserted an 's'
Merge pull request #864 from openscad/bugfix/cmd_save

Bugfix: Cmd-S on an unmodified document inserted an 's'
Use const for std::string arguments.
Set default font and add loading of additional fontconfig config file.
Add /Library/Fonts for MacOS.
Remove unused path lookup and move OPENSCAD_FONT_PATH to fontconfig.
Show font path in Library Info window.
Camera handling: Double click on a point of an object to set the camera center
Fix render issue with combining chars intersecting with the base char.

Example: text("A\u030A", font = "Arial");

The fix relies on the winding order of the polygons reported by FreeType
to be correct, so the Clipper union operation keeps that information.
Merge pull request #866 from openscad/text-fixes

Text fixes
Merge pull request #865 from openscad/feature/cam_center

Camera handling: Double click on a point of an object to set the camera center
Select charmap when loading fonts and add workaround for windows symbol fonts.
Use special handling for Windows/Symbol charmap only with charcodes >= 0xf000.

Some fonts with symbol encoding still have the charcodes in the ASCII
area instead of Unicode page 0xf000. To make those work too, the special
handling is only enabled in case the first charcode is >= 0xf000.
Add test cases for composition and symbol font handling.
Add example files for text() usage.

The test case images are currently not including the text as the example
test run does not include experimental features. This will need to be
updated once the text() feature is not experimental anymore.
Merge pull request #868 from openscad/text-fixes2

Text fixes (part 2)
Fix FreeType include handling.
Enable IRC notification for travis builds.
Merge branch 'master' of github.com:openscad/openscad into test3dexport
fallback to diffpng if ImageMagick is missing