* Flatten AND, OR & BVPLUS completely via SimplifyTerm

* Flatten AND, OR & BVPLUS completely via SimplifyTerm
* When simplifying don't cache leaves
* Disable the ReferenceCount (which prevents splitting of plus nodes), when using the CVC parser. This was making grep-slow-on-libstp.cvc very slow. SimplifyTerm() was taking more than 5 times as long to achieve a fixed point. The interaction is quite complicated, so for now, I've disabled it.
* Propagate BVUMINUS up through BVMULT.

git-svn-id: https://stp-fast-prover.svn.sourceforge.net/svnroot/stp-fast-prover/trunk/stp@207 e59a4935-1847-0410-ae03-e826735625c1