Merge pull request #1 from openscad/master

update from main
Changed exit codes to 0 and added help description to help menu #1028
Merge branch 'master' of https://github.com/jgelderloos/openscad
Use separate project for winconsole and don't statically link Qt (fixes #870).
Minor Grid3 refactoring
Update offset() parameter handling.

- Rounded offset is now using parameter r
- Using delta only or delta with camfer = false creates no chamfer
- Using delta with chamfer =true creates chamfer at delta distance
Fix color schemes (brace highlight / selection color / line-end markers).
Update lexer keywords.
Allow reading the keyword lists from the color scheme files.
Add keyword lists.
Swap colors so the bright red is only used for language keywords.
Remove eigen2 detection, eigen3 is required.
Catch win32-mingw used when building on MSYS2.
Move -DNOGDI to main project file.

This is not related to the cross build but a workaround when including
windows.h that also defines Polygon. So it's now enabled for all Windows
builds including MSYS2.
Updates to build on MSYS2.
Revert usage of the -Wa,-mbig-obj flag as that does not work on MXE.
Color code warning and error messages in the console window (fixes #855).
Use QtConcurrentRun to initialize FontConfig in a separate thread.
Update test reference file for norm().
Merge pull request #1093 from openscad/warning-highlight

Color code warning and error messages in the console window (fixes #855).