Started work on read/write db interface and DDGPatcher.
Different factories can now be used for CFGForDDG-creation when calling the DDG creator. This is necessary so that we can retrieve CFGForDDGs from the database using a ReadWriteDB-interface in the DDG-patcher.
We can now create CFGForDDGs from both the BatchInserter and the standard embedded neo4j database API. This is necessary for the DDGPatcher since the BatchInserter does not allow us to remove edges.
DDGPatch now retrieves the right functions to patch, hands the corresponding CFGForDDGs to a patching routine and recalculates the DDG.
removed PDG code, which we ended up not using.
Cleanup of DDG creation code before things become too unorganized.
DDG difference calculation.