Adapted cutIntroduction.applyExp into Generalized.cutIntroduction.applyStat to support testing cut introduction with multiple variables on the TSTP data. The call in the shell is:
   cutIntroG.applyStat(ep: (Seq[ExpansionTree], Seq[ExpansionTree]), delta: DeltaVector, [prover: Prover]) : (Option[LKProof], String, String)

   where possible values for delta are 'new OneVariableDelta()', 'new UnboundedVariableDelta()', or 'new ManyVariableDelta(n: Int)', representing the delta-vector, generalized delta vector, and the (upper)bounded generalized delta vector, respectively.

git-svn-id: http://gapt.googlecode.com/svn/trunk/source@1783 85d21ef8-add0-11de-ae77-5bfb9c5a3f34