Made the signature provider functional

[RSDuck]

As far as I tested it, it worked including that it shows which parameter is currently selected and that when a procedure is called with the object.procedure(object goes into first parameter) syntax it automaticly jumps to the second parameter.
In some rare occasions it is a little bit wonky because of NimSuggest(for example when there is already written if == 0: and you want to write the part before the ==), but in most cases it works perfectly.

Also as a small addition I added " as brackets, so when one is typed the other gets inserted automaticly and added to the hover provider that it shows also the type of a symbol.

[oderwat]

Cool!

But I noticed that if you have multiple signature matches (I have 4 in my example here http://www.giphy.com/gifs/l46CCqJCiUvwDHkMU) and you move lets say to the second one, it jumps back to the first one when you start typing anything. I guess it updates with a new nimsuggest result. But maybe one could leave it on the same selection until the results from nimsuggest differ. Maybe even stay on the selected one as long as it is part of the results from nimsuggest.

[RSDuck]

I looked up, there is no way to get the currently selected signature. So it isn't possible to do something like that.