- Fix the bug where history was not working correctly
 - Refactored code for evaluator running in Threads.
 - Tab size is now smaller
Some refactoring:
 - Evaluator now returns EvalResult
 - Refactored outputstream and interfaces
outputstream now handles output in pieces, fixes the holdup for large pieces of text. That is: Both a lot of printlines as well as large strings.

Note: The placing of characters could use a small cleanup
Added import mechanism for rascal
Cleaned up language interface
Removed other languages for now
Refactored some other pieces of code
Added other type of command symbols