Added functional interface types (Java)

Mwahaha, Jared you will have to review this :manic_laugther:

This time for nonexpansions.
The method signatures should be calculated correctly now, though they are still only filled with nulls

Was an instance field all along, but always set to null

Fixed functions not working properly

Signature: Include the type in the signature if it is an expansion method
Call: Call invokeStatic if its an expansion method

fixes issue about unknown type parameters for StdLibs::List

Functional interface wrappers should work now
Implementing a method with a signature differing from the actual one (e.g. when dealing with generics) now creates a proper bridge method
The Java Bytecde compiler used an incorrect method in checkCast
We now no longer use hardcoded 'accept's as method names but whatever the context tells us to.

Directly using the lambda where the functional interface is requested works.
The lambda class will then directly implement the functionalInterface and not use a wrapper class

- Save collapse state of the project browser tree

- Added support to have a native method both as operator and named method

- WIP on map files (used to link zencode to already compiled classes, and to define native methods)

- Fix default constructor not working properly
- Fix integration classes without exposed constructor being instantiable if they have a default (non-exposed) constructor
- Fix extern methods failing validation

- Simplified compilation process somewhat; removed CompilationUnit class and work more module-oriented instead

- Fixed a couple minor issues & inefficiencies
- Added horizontal scrollbar to IDE (incomplete!)

- Slightly improved the way modules are compiled

- Removed export access and added internal access support