Added local variable lookup support

Been looking at this for awhile, decided to try it out, was saddened to
find class member auto-completion but no local auto-completion but love
what has been done so far, so I went ahead and added it.

My Python is a little rusty, and the ST2 API documentation is really
lacking to me, but maybe this is helpful? Its helpful to me :D

I tried adding conforming code and comments according to the current
style, if there are any stylisic errors, please point them out and I'll
be glad to conform.

Thanks Zinggi for getting what has been done done so far and putting it
out for the public!