Updated Todo
Added a Set Subtraction Function

Checks for equal elements and subtracts them, currently doesn't work.
Fixed Subtraction Function

Modified subtraction to go through all of the second sets children,
rather than walking through each set at the same speed.
Added Intersection Method and x6 Output

Completes the assignment part-1.

Intersection is almost an exact copy of subtraction.
Updated TODO.md with new Bugs
Updated makefile to Comply with Spec