If and While loops.

[TzurSoffer]

Added while loops and conditional statements in PR (#316 ). It could still be optimized and nested while loops don't work. Everything else, however, does work, including IF, ELSE IF, ELSE, WHILE, and nesting (as long as it's not nesting while loops). This PR depends on the variable math PR (#304 ). Please merge that one before the If and While loops. I plan to fix the nested while loops issue soon.