Add infolabel Control.GetLabel2() and the ability to get an edit controls edit text

This allows getting a controls second label via an infolabel. Here it is only currently implemented for CGUIEditControl, as this is necessary for the Text To Speech addon to get keyboard dialog text in Helix. If this looks good, I will in the future implement it for other controls.

It seems to work fine, but please have a look and let me know if I should do something differently as I barely know what I'm doing :)

If all is well, it would be great if this could get into Helix, as the keyboard dialog is now useless for blind users.