Changes:
0.8.4:

PC-FX: Some RAINBOW registers weren´t being reset on emulated system reset. Fixed.

PC-FX: Added dummy support for the external bus reset register.

PC-FX: Altered the way garbage data is handled by RAINBOW to fix a graphics bug in the Tengai Makyu options screen.

PC-FX: Reworked a large part of the KING SCSI emulation code, and parts of the CDROM device emulation code. Previously non-working-at-all games
"Battle Heat" and "Tengai Makyu" work now.
The non-anime game mode in "Tyoushin Heiki Zeroigar" works now. "Der Langrisser FX" no longer locks up if you skip the intro movie.
"Yuna FX" no longer locks up in one of the intro movies.
These changes will cause some save state incompatibilities with previous versions of Mednafen.
(Some of the SCSI changes also affect the PCE CDROM emulation, which may also result in save-state incompatibility issues, particularly if
the save state occurred during a CDROM data transfer operation.)

PC-FX: Added setting "pcfx.cdspeed". If you want to change this, read the documentation first!

Cleaned up the video deinitialization code slightly, and fixed a few bugs in the OpenGL deinitialization code.

PC-FX: Reads from the dummy KING register 0x07 will now return 0xFF, per the devkit docs.

PC-FX: Reads from KING register 0x0B will now return the "DMA end" bit in D0 set correctly(at least, according to the developer docs).

Fixed a compilation error after running configure with --disable-nes.

PC-FX: Reads from I/O port 0xFC0 will *now* return the current timer counter value. The switch statement mask value was wrong...

Removed the warning in the documentation about error correction of raw data track rips, as Mednafen will now perform simple correction
using the EDC and L-EC data(since 0.8.4-rc3). This could conceivably cause problems with naive hacks/translations/patches that neglect to update
the EDC and L-EC data, so it can be disabled by setting the setting "cdrom.lec_eval" to 0.
L-EC correction is based off code from dvdisaster(http://dvdisaster.net/).

PCE, PC-FX: Removed some debug printf()´s that were left in 0.8.4-rc3 by mistake.