Add support for gameboy color

[alloncm]

In order to do that there are a few areas that will need to change

• Detect rom target machine (CGB/DMG)
• CPU - support double speed mode, including enable and disable double speed mode
• PPU -
  • Support the CGB pallets
  • Object priority changes in CGB mode (place in OAM memory and not X value)
  • BG map priority table
• MMU
  • Support the expanded vram and ram
  • Support the new vram dma contoller
  • Support the CGB bootrom

[alloncm]

• Add expected hardware detection based on the cartridge
• Add support for double speed mode
• Add support for loading the new bootrom

[alloncm]

Currently all the features are implemented in the branch.

There still some bugs I have seen them in pokemon yellow

• Problems with the colors
• Problems with memory locking and timing, writes to vram during pixel trasfer stage