If 'true', then places representing sequence flows that have no
user-defined label in the BPMN-model will be given generic labels (based
on labels of source/target nodes).
How to label elements of the generated Petri net, default is to prefix
every element which is not a task with a prefix telling which BPMN
construct it belongs to.
Discovering dominators, post-dominators and enclosing subprocess for graph nodes
For the algorithm description see http://en.wikipedia.org/wiki/Dominator_(graph_theory)