Replaced the List of Pairs for abbreviations with a map and added a method to retrieve the abbreviated expression from it.
Replaced the List of Pairs for abbreviations with a map and added a method to retrieve the abbreviated expression from it.

git-svn-id: 81b63372acb31b227ae206b0e193c75f469b8824@18158 4712c6d2-40bb-43ae-aa4b-fec3f1bdfe4c

sosy-lab/java-smt,sosy-lab/java-smt,sosy-lab/java-smt,sosy-lab/java-smt,sosy-lab/java-smt