nearly all of the previous required extensions are CORE in OpenGL 2.0
the remaining ones need to have fallback checks for ARB vs EXT vs APPLE
variants..
The general rule I'm aiming for is to <> include
system wide / installed paths / generally everything
that's outside the git managed source tree (this means
mruby paths too!), and "" include everything else,
ie. local mkxp headers.
The only current exception are the mri headers, which
all have './' at their front as to not clash with
system wide ruby headers. I'm leaving them be for now
until I can come up with a better general solution.
Using "SDL2/SDL_xxx.h" instead of "SDL_xxx.h" caused
the include paths provided by pkg-config to be ignored,
and headers from a standard include path to be used instead.
The drawing is now completely shader based, which makes away
with all usage of the depracted matrix stack. This also allows
us to do things like simple translations and texture coordinate
translation directly instead of doing everything indirectly
through matrices.
Fixed vertex attributes ('vertexPointer()' etc) are also
replaced with user defined attribute arrays.
Edward Rudd
Jonas Kulla