Allow BlockEncoding for path programs

[danieldietsch]

BlockEncodingV2 should provide an API s.t. other plugins can use it to block-encode arbitrary IIcfgs (especially PathPrograms).

First proof-of-concept should be implemented in PathInvariantsGenerator:

ultimate/trunk/source/TraceAbstraction/src/de/uni_freiburg/informatik/ultimate/plugins/generator/traceabstraction/pathinvariants/PathInvariantsGenerator.java

Line 255 in e710831

// TODO: add here some code that transforms the pathProgram icfg

Besides block encoding, the result should also provide some backtranslation information (at least a mapping from old locations to new ones)