Beta 5:

Biggest A500 cycle-exact updates should be done now.

* interrupt delay rewritten and corrected, fixes Gleat Stuff #01/BRB
* blitter/CPU timing tweak, fixes 1010 bobs/Celtic
* disable sound if sound driver buffer position gets stuck (driver bug)
* final partition read/write fix
* try to emulate reading of non-existing/write-only custom registers more accurately
* Brian the Lion "dialog screen" seems to be something AGA specific after all... 1 extra cycle needed after write to BPLCON0 before BPL cycle diagram changes (or at least in Brian the Lionīs situation) so add one cycle in AGA and hope it isnīt totally incorrect fix