some minor additions to lambda calculus (added symbols method) and some scope changes for quantifiers in fol

git-svn-id: http://gapt.googlecode.com/svn/trunk/source@1563 85d21ef8-add0-11de-ae77-5bfb9c5a3f34
added tests for bound variable normalization

git-svn-id: http://gapt.googlecode.com/svn/trunk/source@1564 85d21ef8-add0-11de-ae77-5bfb9c5a3f34