Feature/bytecode types

[BitDragon256]

Resolves #27

This PR adds all native java types to the bytecode generator. Those are: byte, char, short, long, float, double. The arithmetic operations should all work, only the char type I couldn't test as it isn't yet supported by the semantic check.
I also needed to make some changes to the type handling in the background (in the stack and local variables), but those should not break any existing features.

[BitDragon256]

I just noticed that the tests are not running, will resolve this first

[Brofian]

I took the liberty to fix the bug that prevented chars from being recognized. The problem was, that the parser included the quotes of String- and char-literals in the value string. This caused all of them to be recognized as strings.
Also: you committed .class files inside the input directory. As I am sure, that was an accident, it removed them :)