Implemented the unsound approach of adding pre-loop information to the induction hypothesis of k-induction. This approach was introduced by the SV-COMP 2013 competition contribution of ESBMC 1.20.

git-svn-id: https://svn.sosy-lab.org/software/cpachecker/trunk@13195 4712c6d2-40bb-43ae-aa4b-fec3f1bdfe4c