Commit the rest of the OSX build fixes missed in the previous commit.
Pcbnew: fix Bug #1380943 (Filled polygons with thick outlines are missing last outline thick segment in gerber)
Remove a debug message in searchhelpfilefullpath.cpp.
Fix install location of fp-lib-table in scripts/library-repos-install.sh.
Pcbnew VRML export improvements.

* Improve VRML export dialog lay out.
* Make the OK button the default action in the export dialog.
* Make 3D model export work correctly and avoid redundant file copies.
* Fix embedded path separators in wrl files on windows.
* Fix absolute model file path creation in wrl files.
* Clean up VRML export code.
Python scripting: make UTF8 class accessible by python scripts. Add python method GetChars() to UTF8 class to get its char buffer.
See scripts/test_kicad_plugin.py for example.
scripts/test_kicad_plugin.py cleanup
Add stable release policy to developers documentation.

* Write stable-release-policy.md for upcoming stable release.
* Remove unused Doxygen options from Doxyfile.
Fix MSYS2 build configuration issues.
Add missing source file licenses and code policy fixes.
More source file missing license fixes.
Minor improvements to kicad-install.sh.

* Exit script when package install, build configuration, or build fails.
* Install each dependency package one at a time.
More missing source license fixes.
Fix kicad-install.sh to only install wxPython when building with scripting enabled.
python scripting: refinement for UTF8 class (from Miguel Ángel Ajo Pelayo) add __str__  method, usefull to print a UTF8 string.
Kicad manager: fix issues in file watcher: changes (adding/removing files)  in project folder not seen by Kicad manager (perhaps due to changes in internal wxWidgets code between 2.9.5 and 3.0).
More missing source license fixes.
* Update AUTHORS.txt with more valuable contributors
* Add Cirilo Bernardo as contributor in AUTHORS.txt
change malformed comments in kicad.i