Closes #51. Implement Splats

[faultyserver]

Simple Splats are now supported for use as Call arguments, List literal elements, and for general use. They are implemented using a unary * method definition on the receiving object.

Splats currently enforce that the result of calling the unary * method will be a List value. I'm not sure if this is entirely desirable, but it can be changed in the future if it is not. #51 may be a place to continue discussion on this.

Additionally, an implementation of the splat operation for Lists has been added to support the most common usecase:

def foo(a, b, c)
  a + b + c
end

foo(*[1, 2, 3]) #=> 6