clone sdl2gl2 into sdl2gl3
request GL 3.0 context
GL 3.0 initial operational capability
fix string shrinker
drop some commented code
report mouse button events' grid position
fix an off-by-one in grid flip
fix horrible typo
fix button enum to coincide with SDL1.2 values
mouse support, continuous draw still broken
make sdl2gl3 the default renderer
fix FPS calc and display
actually return FPS, not the milliseconds
dump it better
fix offscreen buffer fill-out
add an important comment
drop unused code
GL3 offscreen renderer - IOC
update todo list