Add advanced tests
Improve meet in set lattice
Prepare for abstract timestamps
Use new timestamps in CESK
Allow to tick on value states
Fix visualisation
Merge same continuations together
Add kont_equals and value_equals
Remember visited states
Use Pervasives.compare when possible
Don't store the primitive functional value in the primitive, to keep them comparable
Remove compare_node
Add colors to output
Disable verbosity by default
Fix advanced tests
Fix visualisation
Avoid collisions in vertex names
Don't need to loop over all continuations when stepping nodes