I added support for while and for loops. The syntax is just like C/Java:

while(<cond>) {}
for(<start>; <cond>; <update>) {}

Loops support break/continue just like C/Java.

I did not add support for labeled breaks and continues. It's kind of obscure, and I'm not sure how the label with a colon will fit into the grammar yet. It will be easy to add if we decide to do that.

I also didn't support comma listed expressions in the for loop. Opinions?

I also did a lot of refactoring to cleanup the code and make error checking more robust.

We need comma listed expressions - that is very convient in certain situations.