Fixed extending classes

Classes with a "merge" or "each" property would cause an error when
extended.
Improved/extended operators as functions

Moved "System.Comparators" to "jar.lang.operations.Comparison".
Added "Arithmetic", "Bitwise" and "Logical" operators.
Operators always expect two arguments.
Passing one argument returns a right-curried function:
subtractOne = Arithmetic.subtract(1) -> subtractOne(7) -> 6.