Pitch scale

This is the fist chunk of commits, that fixes the scale jump issue of the pitch knob. 
https://bugs.launchpad.net/mixxx/+bug/1258617
The code is still a bit ugly because it still uses the old pitch adjust CO internally but it works. 
I am working on a solution where we just pass pitch and tempo to the scalers, which will clean up the code.
I think it's ok that it adjusts the pitch and the locking, but that's inevitably true because that's what keylock does.  It is understood in the code that keylock adjusts the pitch, so I don't think we need the name to be so long.