Beta 5:

- moved file extension stuff to half-empty priority panel, replaced button with list and added (de)associate all buttons. Extension command line visible and editable? Perhaps later..
- Improved emulation of reads from write-only custom register after some boring real Amiga testing.. (still not exactly right) S.E.X by Fantasys works now. (does MOVE.L INTREQ,D0 when it should have been MOVE.W INTREQR,D0.. This only worked accidentally)
- EDIT: forget about this one, there seems to be much better way to do this.. [Picasso96 vblank wait implemented without busy waiting. Was in pre 1.5.0 but busy waited, was "lost" when RTG was rewritte]
- sometimes first vertical blank interrupt was missed when loading statefile if statefile was created when blitter was active