Added SquareEdges2DimExampleProof (a variant of SquareEdgesExampleProof which uses sx,ys,a,b instead of just s,0 for natural numbers) to /testing. Put corresponding command into the cli and its help text.

git-svn-id: http://gapt.googlecode.com/svn/trunk/source@1527 85d21ef8-add0-11de-ae77-5bfb9c5a3f34