Attempt to get Mirax up and Running (#170)

* Attempt to get Mirax up and Running

With thanks to dink for spotting a mistake with the CPU
decryption i'd made which stopped the sound from working.

MAME WIP

0.145u6: Stephane Humbert fixed dipswitches and inputs in Mirax (after verification of the Z80 code) and removed unnecessary notes. Angelo Salese implemented flip screen support to Mirax. Added dipswitches 'Cabinet', 'Flip Screen', 'Bonus Life', 'Flags for Extra Life', 'Difficulty' and 4x 'Unused'.

0.134u1: Stefan Lindberg added clone Mirax (set 2), correct Mirax clock frequencies. Changed Z80 CPU1/2 and the 2x AY-3-8910A clock speeds to 3MHz.

0.132: Olivier Galibert, Angelo Salese and Tomasz Slanina fixed Mirax - Game now playable. Tomasz Slanina fixed rom 2 decryption. Angelo Salese improved the video emulation. Olivier Galibert fixed address line swapping in Mirax. Changed region gfx3 to gfx2. Fixed gfx2 rom loading. Changed Z80 CPU1/2 clock speeds to 6MHz and visible area to 240x256. Added Player 1-2, 8-way Joystick, 1x button and 2x coin slots. Added dipswitches 'Coinage', 'Lives', 'DSW_BANK2', 'Demo Sounds', 'Allow Continue', 'Auto-Play Mode (Debug)' and 8x 'Unknown'.

7th June 2009: Angelo Salese - Thanks to the decryption aid from OG and Dox, we've finally got Mirax to the working state in the last couple of days.

0.131u4: Olivier Galibert decrypted Mirax main program roms. Added 2nd Z80 (12MHz) CPU2. Changed region maincpu to audiocpu and user1 to maincpu.

0.131u3: Angelo Salese decoded color proms and fixed bitplanes in Mirax.

0.103u1: Tomasz Slanina added Mirax (Current Technologies 1985).

* Whoops

* Ole style dips