graph.gv: Added example GV file from GraphViz web

Shows an example of a DFSM.
.gitignore: Cleared; added graph.png

graph.png is default output when graph.gv is rendered with GraphViz.
graph.gv: Added simple diagram of Pac-Man

Removed original example. Added high abstraction level diagram of
Pac-Man.
graph.gv: Renamed nodes, added some arcs and nodes

Lower abstraction.
Lower abstraction
Lower abstraction; arc names start in uppercase
graph.gv: Even more detail
graph.gv: Improved comments