mc6847: Fixed text display with external rom: fixes spc1000 and phc25
mcu undumpable internal rom sadness.
Probably the only game that would require it is gobyrc/rcdego?
(MESS) gameboy/gbcolor: fixed NVRAM saving. [Fabio Priuli]

out of whatsnew: huge thanks to Shoegazer for reporting the problem!
(MESS) phc25 : added cursor and wave sound.
Cleanups to the file selector menus
(MESS) apf : added homebrew to software list
(MESS) i8530h31 now *almost* boots or at least make some beeps, instead of halting because of unmapped I/O accesses, or halting because of a bad checksum because the ROM was loaded improperly. [alegend45]
Clears port a and port b latches at startup, temporarily reverted CA1 timing change as Beezer is extremely sensitive to CB2 timing, temporarily prevented port a read handlers from affecting reading back of output bits (real hardware can do this but some handlers are returning 0 for bits that they aren't driving low). [smf]