Refactoring: Split Dominance-Tree Computation and use Guava classes

Class ‘Dominance‘ has been split into its separate components that are now located in the new ‘util.graph.dominance‘ package. Additionally, for a lot of functionality, Guava‘s graph classes and interfaces are used instead of custom implementations, which should improve interoperability and require less code.

git-svn-id: https://svn.sosy-lab.org/software/cpachecker/branches/graph-dominance@40392 4712c6d2-40bb-43ae-aa4b-fec3f1bdfe4c