fixed a bug in hol2fol, getAllPositions does not fail on abstractions anymore, more tests for lambda terms and maps/sets

git-svn-id: http://gapt.googlecode.com/svn/trunk/source@2215 85d21ef8-add0-11de-ae77-5bfb9c5a3f34
MaxSAT: fixed some comments
TreeGrammarDecomposition: fixed a bug leading to a possible wrong MinCostSAT formulation when iterating over all keys and their respective rests
FlatTermSet: added an additional output to FlatTermSetException to know what we are dealing with, if thrown

git-svn-id: http://gapt.googlecode.com/svn/trunk/source@2216 85d21ef8-add0-11de-ae77-5bfb9c5a3f34