Loop improvements, and assigment operators

Changes:

• End2end test improvements
  • Added command line arguments to get errors
  • Changed printed formatting for easier reading
  • Removed some commented tests that were never gonna be used in that same state
• Fixed bug in for-loop iterators where you can only put integer expressions are from to till. Now you can put any expression there
  • Added end2end tests for these
• Updated the syntax for for-loops:
  • old: for var i = 0 to 100 { } and for var i in arr { }
  • new: for i in 0 to 100 { } and for i in arr { }
• There now is a token!() macro with creates a Token. let token: Token = token!(Plus, "+");
• Updated readme's

Closes LOOP-186, LOOP-187, LOOP-114