- Cherry picked #10662 and fixed merge conflicts.
- Manualy merged the change from #11904.
- Did not merge #12236 since I'm not sure whether the issue
affects Godot 2.1 and I don't have VS2013 to test.
- Did not merge #11843 since it doesn't seem relevant (the
code is only needed for creating DONORS.md, etc.).
- Did not merge #10727 and #11752 since they seem to be
already included in #11742.
- The Windows and Linux builds have been tested with Scons 3.0
using Python 3.
- OSX and iOS should hopefully work but are not tested since
I don't have a Mac.
- Builds using SCons 2.5 and Python 2 should not be impacted.
The reordering of the SConscript includes allows to ensure that
stuff like the builtin zlib headers will be available for libpng.
Also moved glew back into global env, otherwise windows seems
not to find it... Kind of shooting in the dark with this multi-env
setup.
(cherry picked from commit 248bc9159c)