Partly rewrote IKeyboardControl.
Partly rewrote IKeyboardControl.

* Fixed a bug causing (sharp) key coordinates to be 1 pixel off.
* Added DrawKey(), which by default draws "regular" keys using 6 different bitmaps, and sharp/flat keys using a single bitmap. If you need more bitmaps (e.g. because the 1st octave should be gray instead of white), then you can override this method.
* Cleaned up code, especially Draw().

tappleby/hush-vst,tappleby/hush-vst,tappleby/hush-vst,tappleby/hush-vst,tappleby/hush-vst