FDC: Data rate
(use fdc_write_drr, which in libdsk version affects DPB)

> Tidy up presentation:
	* menu drawing code (should look like a 16)
	* window title
	* power switch graphic

> Support for other joysticks than key joysticks:
	* Kempston : Done
	* Spectravideo : Done, untested
	* Cascade : Done, except for up/down axis and UI
	* DKTronics
