Start implementing fixed point back again with *all* the operators.

Add a test for CVC3 fixed point support, and get fixed point working again.
This implements support for the fixed point marker, and make use of it.

The only problem is that literals by default fall down to Reals, so not all
operations are tested.  This needs to be fixed.

git-svn-id: https://groke.mcmaster.ca/svn/grad/colin/branches/TableTool_javization@10709 57e6efec-57d4-0310-aeb1-a6c144bb1a8b