* fixing OpenGL ES 3.0 support in macOS
* make GLES libraries loaded via buildconf vars
* fix relative install paths for macOS
* fix indenting, add comments
* fix indentation for REAL this time (thanks editorconfig)
* Added (and fixed) a few useful warnings
* Removed some dead code
* Cleaned up the build system files a bit
* Once again separated ZIP support from data packaging
* Converted macOS cross-compilation options into cross-file properties