Rename the "stator" package to policyiteration.

Many bugfixes, changes the path focusing approach.
Removes the "stator/memory" package, uses ctoformulaconverter pointer
handling instead.

git-svn-id: https://svn.sosy-lab.org/software/cpachecker/trunk@14650 4712c6d2-40bb-43ae-aa4b-fec3f1bdfe4c