This makes SimplifyTerm idempotent. My hope is that this will reduce the number of...

This makes SimplifyTerm idempotent. My hope is that this will reduce the number of times that the toplevel function needs to be called. If a term at the bottom of the graph doesn't map to itself when SimplifyTerm is run, then all the nodes above it will need to be re-created next time SimplifyTerm is called on the graph.

This patch adds an assertion function that isn't enabled.

git-svn-id: https://stp-fast-prover.svn.sourceforge.net/svnroot/stp-fast-prover/trunk/stp@830 e59a4935-1847-0410-ae03-e826735625c1