get new test in infrastrucutre
generalize regression testing infrastructure

generalize regression test infrastructure so that a test can be added
simply be adding a file to the test directory
added robustness checking to test harness
debugging bad arithmetic expression
Minor modifications
Merge branch 'hashval' of https://github.com/thomasjball/PyExZ3 into hashval

Conflicts:
	test/se_descr.py
debugging...
Merge branch 'hashval' of https://github.com/thomasjball/PyExZ3 into hashval
more debugging
even more debugging...
another one...
Merge branch 'hashval' of https://github.com/thomasjball/PyExZ3 into hashval
finally found the source of problem (no radd)

Major problems in code - doesn't handle general expressions!
beef up overloads for symbolic types
hashval is now working!
add non-standard integer semantics to match BV