-------------------------------------
Format of SMSAdvance (v1) GBA images:
-------------------------------------

???? bytes:  SMSAdvance.gba contents
(optional) 76800 bytes:  Splash screen (raw 240x160 15bit image)
----
4 bytes:  Identifier = "SMS",0x1A
4 bytes:  ROM size
2 bytes:  ROM flags
1 byte:   Branch hacks, bit 0-3: opcode, bit 4-7: length. (not yet).
1 byte:   Reserved (set to 0)
4 bytes:  Autoscroll value (a.k.a. "sprite following")
1 byte:   BIOS flag, bit0=1 for BIOS rom.
15 bytes: Reserved (set to 0)
32 bytes: ROM title (NULL terminated)
???? bytes:  ROM contents (.SMS format)
----
4 bytes:  Next ROM indentifier
etc etc...
----

ROM flags:
    Bit 0: Use PAL timing
           (0=NTSC, 1=PAL)
    Bit 1: Domestic bit
           (0=Usa/Europe, 1=Japan)
    Bit 2: GameGear
           (0=SMS, 1=GG)
    Bit 3: SMS2
           (0=SMS, 1=SMS2)
    Bit 4: Enable CPU speed hack
           (Enables the branch hacks)
    Bit 5: 0=Autoscroll value is a sprite number
           1=Autoscroll value is a memory location
    Everything else:  Reserved (set to 0)


