refactored TreeGrammarDeccomposition for implementing another formulation for MinCostSAT

git-svn-id: http://gapt.googlecode.com/svn/trunk/source@2104 85d21ef8-add0-11de-ae77-5bfb9c5a3f34
Fixed a bug in suffKeys of TreeGrammarDecomposition, which lead to a performance issue, due to the necessity of constructing the whole powerset of st(L) and not just all subsets of size at most n+1.

git-svn-id: http://gapt.googlecode.com/svn/trunk/source@2105 85d21ef8-add0-11de-ae77-5bfb9c5a3f34
removed unnecessary debug outputs in TreeGrammarDecomposition

git-svn-id: http://gapt.googlecode.com/svn/trunk/source@2106 85d21ef8-add0-11de-ae77-5bfb9c5a3f34