Bump submodule to get a fix to grammar.cma

Needed for dpdgraph on travis.
Update dpdgraph to compile with current trunk
Fix the stackoverflow in dot

It was caused by the self-referential nature of primitive projections.
Rather than filter this out in Coq-land, we simply ignore requests to
add self-edges in dot-land.
Correctly handle cycles in dpd2dot
Merge pull request #650 from JasonGross/fix-dpd-graph

Fix dpdgraph