Removed all known GLEW workarounds, added one small workaround for
missing ARB_texture_compression_bptc. I didn't want to patch glLoadGen
for just four enum values, this way it's possible to use stock one
without any patching (except for missing OpenGL 2.1 support, as stated
in external/OpenGL/GL/README.md).
As one file now replaces both `glew.h` and `glcorearb.h` and it has the
same size as `glcorearb.h` alone , it saves approximately 18k LOC,
resulting in 15 second shorter compilation time (5:03 before, 4:48 now).
Not bad.
In next few commits AbstractFont will become plugin interface. Font
implementations are now in magnum-plugins repository. Removed all traces
of FreeType and HarfBuzz dependencies.
Makes it easier to disable parts of the code than with this. And this
would also not be future-proof:
defined(MAGNUM_TARGET_GLES) && !defined(MAGNUM_TARGET_GLES2)