Adding Guard and Assignment interfaces as discussed.
Some tidying up and rearranging. Small-Step has been renamed as
incremental as I think it sounds nice. Also organised monitoring.impl
into packages.
Fixed a few things that were stopping the tests from running. The main
thing was adding Quantification to structure - allowing us to properly
indicate the quantification (universal,existential or none).
Fixed SimpeNonDeterministicQEA.getNextStates. The issue was that an
iteration variable was being used instead of the value it was supposed
to point to. Also added test for this case.
Some more refactoring to share similar bits of code, and renaming to
make things uniform.