Some cleanup, added null check functionality on arrays. Test.hs correctly tests all 16 examples now.

Implemented Wishnu’s idea for quantifier evaluation in the Test module, since that’s definitely a better idea on second thought. However, performance with complete randomness is absolutely terrible now, so that problem needs to be addressed next.

- Fixed bug that caused extractExpr to crash when it tried to fetch all pre / post conditions of a method that doesn’t have any.
- Increased the number of iterations in the tenth LogicIR.Backend.Test test.

Renamed QuickCheck to Test everywhere, since QuickCheck isn’t even used in the automated testing module.

- Added correct handling of LIsnull in QuickCheck.
- Fixed a bug in Rewrite.hs that wasn’t causing issues yet, but was a bug nonetheless.
- Sped up QuickCheck tests by making the number of iterations dependent on the specific test.

  - Fixed bug that caused some QuickCheck tests to throw an exception because not a complete substitution was taking place.
  - Uncommented the legendary 16th bug that causes an endless loop when Z3 is used. It doesn’t cause an endless loop with QuickCheck, but QuickCheck does give the wrong answer :’(.

All in all, the very naive testing module correctly tests 13/16 tests at the moment (most of the time at least; it’s random).

- Removed the eval tests.
- Added tests for QuickCheck
- Note that something is broken: multiple tests fail.

- wrote a function in SimpleFormulaChecker.hs that can be used to evaluate (for now just preconditions) in java files;
- wrote some (for now) very basic tests for LExpr eval;
- worked on QuickCheck.hs, but I have some ideas (mainly regarding arrays) that I need to discuss before I proceed;
- added extra parentheses in Pretty.hs to make debugging the AST easier.

#15

does not actually work though

Closes #13

closes #10