INES Mapper 165

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 Here are Disch's original notes:  
 =  Mapper 165          =
 Example Games:
 Fire Emblem (Unl)  (some weird ?Chinese? pirate version)
 This mapper is a strange MMC2+MMC3 hybrid.  Register style, PRG, mirroring, ?and even IRQs? of MMC3, with the
 CHR swapping and CHR latch functionality of MMC2.
 There is 4k CHR-RAM in addition to any CHR-ROM present.
 For details on MMC3, see mapper 004.  For details on MMC2, see mapper 009.  Both will be referenced heavily
 in this doc.
 Register layout, PRG Setup, SRAM enabling, Mirroring, all function as they do on your vanilla MMC3.
 The CHR Regs (R:0 - R:5) are used in MMC2 style:
 CHR Setup:
       $0000   $0400   $0800   $0C00   $1000   $1400   $1800   $1C00 
     |      <<R:0>> or <<R:1>>       |      <<R:2>> or <<R:4>>       |
 The same latches that exist on MMC2 exist on this mapper as well, and determine the appropriate reg.
 CHR page 0 is CHR-RAM, other pages are CHR-ROM.
 This game specifically will read ppu$xFD0 or ppu$xFE0 via $2007 to manually toggle the latch (specifically,
 to swap in the CHR-RAM page).  Failure to emulate this method of MMC2 latch toggling will result in garbled