[scad-mode] Improved package description
Merge pull request #827 from purcell/patch-1

[scad-mode] Improved package description
Mac: Automate build with libc++ when not using OPENSCAD_LIBRARIES

Conflicts:
	openscad.pro
Merge remote-tracking branch 'origin/mac_libc++_build' into c++11
Adapt to using CONFIG+=c++11