Added nodeProgramEnd to tell when we exit main(). Currently all function definitions occur right after main and the programEnd is a useful way to stop running into those functions.
Currently the evalutationStack is using a queue structure which doesn't have a way set the stack position manually as is required when returning from a function call and the local variables have to be removed from the stack. The next few submission should address this issue.
Function call stack much more robust. Stack frame gets sets up with respect to base pointer and then gets restored when exiting function. Still work to do on accessing function parameters correctly. Also, making a call to an intrinsic function like moveAbsolute() clearnly not working yet. Also, need to return automatic and temporary function variables to the pool of available symbols otherwise we'll quickly run out of space.