Remove the enum ViolatedProperty with hard-coded possible properties
to be violated.
Instead, there is now a string which should contain the human-readable reason
for the result unsafe,
and it is expected that the specification automata are used
to declare these reasons
(so that none of them appears in the actual source code of CPAchecker).
Furthermore, another advantage is that the message can be more flexible,
e.g., contain the line number.

git-svn-id: https://svn.sosy-lab.org/software/cpachecker/trunk@13113 4712c6d2-40bb-43ae-aa4b-fec3f1bdfe4c