Fixed bug(s) in evalBin
Equivalence class tests also use the QuickCheck module now.
Added a "run mode" to Main.hs (Debug / Release). In case of Debug, the results of QuickCheck and Z3 will be compared (and an error will be thrown if they have different results). In Release mode, this doesn’t happen.

Refactored Test code to work with Z3 code.
Integrated Test module in Server code.

- 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.

- 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.