Fixed a blending bug caused by imperfect half colour behaviour in Soul Blazer. The half math now shouldn't take the back colour into account:

[Linked Image from mamedev.emulab.it]

[Linked Image from mamedev.emulab.it]

@Arbee: there's already a system like that in MAME, it's the Neo-Geo -bios 9 (aka the "Custom Japanese Hotel"). In my humble opinion that's eligible like the Playchoice-10 or the MegaTech.