tex output: render dot automata

[pazz]

Since we're anyway in the business of calling external binaries for creating nice PDF outputs, we may as well render DOT automata as png and then include the graphic in the generated tex.

 dot -T png bottleneck-2-abcde.dot -o example.png

[Numero7]

yes sure. there is a script in examples/ to produce pdf from dots, it could also produce pngs if needed.

[Numero7]

@pazz