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
Fix scoping issues when evaluating $vpt, $vpr, $vpd.
Match gimbal camera orientation with values shown in GUI.
Setup camera distance for both perspective and orthogonal mode.
Update camera settings for camortho test and update reference image.