Add some miscellaneous tests
Add some miscellaneous tests

When I started developing the new C expression module,
I referred to it as 'exxpr' to differentiate it from the expr module.
This is some leftover code from then,
which should eventually be refactored or discarded.

pombredanne/pyeda,karissa/pyeda,GtTmy/pyeda,sschnug/pyeda,pombredanne/pyeda,GtTmy/pyeda,karissa/pyeda,cjdrake/pyeda,cjdrake/pyeda,sschnug/pyeda,cjdrake/pyeda,sschnug/pyeda,GtTmy/pyeda,pombredanne/pyeda,karissa/pyeda