Bugfix. Infinite loop. My fourth attempt to fix the problem introduced in r947. I...

Bugfix. Infinite loop. My fourth attempt to fix the problem introduced in r947. I've been careful this time.

Refactor. Remove explicit calls to SimplifyTerm if simplify_upfront is enabled. This is a precursor to removing many of the SimplifyTerm calls in the SimplifyTerm function, nearly all are redundant because at the end of the function we have:

    if (inputterm != output)
    	output = SimplifyTerm(output);

i.e. we fixed point it.

git-svn-id: https://stp-fast-prover.svn.sourceforge.net/svnroot/stp-fast-prover/trunk/stp@964 e59a4935-1847-0410-ae03-e826735625c1