feature/new parser on kore

**please review** @dwightguth 

A bit of context:
take textual full K outer definition ( with KAST inner)
->
KIL outer + bubbles
-> via KIL-to-KORE
KORE outer + bubble
->
parse KAST bubbles with new parser using a KORE outer definition of KAST (from kore.k)
->
complete KORE :-)

@radumereuta, this is the work we did last week. I fixed some tests and cleaned up a bit. have a look and adjust as you see fit.
I thought about this but didn't really want to create a precedent. Initially I didn't like that the KORE classes cannot depend on existing code, but it may be for the best in order to not muddy the waters. 

The existing POSet implementation is pretty clean but it is mutable. As I need the poset as a field of an immutable KORE class, I wouldn't plug it in directly. One way would be to use it to compute the transitive closure, then wrap it in an immutable data structure. The the Java POSet object will only live during the computation. I didn't think it is worth it considering the simplicity of doing a transitive closure. Still, yes, it is workable, and I can take this path if it pleases people. Let me know.