This will allow to save hotkey option toggling to the ini which
should fix gui updating with hotkey toggles.
Note: Render hw/sw switch doesn't work.
Also update some options that didn't have hotkey nametag.
* Add full PMODE register to replace slbg/mmod
* Add full EXTBUF register (will allow to emulate write feedback)
* Add a third source (which will actually be the destination of the
write feedback)