fixed a bug in TreeGrammarDecompositions method for calculating normform and characteristic partitions, resulting in a wrong set of keys in cases of n >= 2

git-svn-id: http://gapt.googlecode.com/svn/trunk/source@2102 85d21ef8-add0-11de-ae77-5bfb9c5a3f34
slight code clean up in TreeGrammarDecomposition
added ncutIntro to the cli
added NCutIntroduction
still not usable due to a NullPointerException in NCutIntroduction

git-svn-id: http://gapt.googlecode.com/svn/trunk/source@2103 85d21ef8-add0-11de-ae77-5bfb9c5a3f34