Fixing bug in draw_slice

`call_draw` and `call_draw_indexed` expect (start, count) but
where given (start, end)
Merge pull request #458 from juxiliary/master

Fixing bug in draw_slice
Merge pull request #456 from serpis/master

Set color buffer outputs when using multiple color targets.
update to new glfw key event function to fix compile error
Merge pull request #466 from linuxaged/master

update to new glfw key event function to fix compile error