Grab documentation and put it in the debug output.

I thought it might be fun to find the Haxe documentation for the function you're trying to call and show the user that doc somewhere. Currently I just put it in the debug window. I'm actually not sure what would be better, so if you have any ideas, let me know.

I cache the documentation in a dictionary called `documentationStore`. This saves us from hitting the haxe server twice in a single function call.