Fix set_state, unset_state typos in doc.  Add TOC to graphics chapter.
Fix set_state, unset_state typos in doc.  Add TOC to graphics chapter.

oktayacikalin/pyglet,theblacklion/pyglet,mammadori/pyglet,oktayacikalin/pyglet,oktayacikalin/pyglet,theblacklion/pyglet,mammadori/pyglet,theblacklion/pyglet,mammadori/pyglet,mammadori/pyglet,oktayacikalin/pyglet,oktayacikalin/pyglet,theblacklion/pyglet,theblacklion/pyglet