Add support for ARB_draw_instanced and ARB_instanced_arrays
OpenGL::Modern has support for these: see https://metacpan.org/pod/OpenGL::Modern#glDrawArraysInstanced
criticisms on the XS code by bulk88
The RPN stuff will be getting deprecated since I'm not convinced it's ever been used. What it was intended for should instead be done with shaders.
conflicting types for 'GLsizeiptr' on 32-bit-architectures
more memory access bugs
Classic vertex buffers registered with glVertexPointer_p causes segfault
Thanks! The latest CPAN OpenGL, 0.7006, has been extensively tested and fixed to work even when $hasVBO is false, so I will close this. If issues recur, please open a GH issue which is now the correct tracker.