Remove unnecessary calls to didChange

[martskins]

I'm not quite sure if this is correct, but all those calls to text_document_did_change seemed unnecessary to me. While removing those I also noticed that our handle_text_change function doesn't really do anything, it used to have a call to text_document_did_change but at some point that got deleted, and it seems to me like we want to have that there, especially if we're removing the other calls.

This also lets us remove the text parameter from the functions that don't really need it, reducing the size of the message considerably.