Fixed incorrect XOR opcodes.
Completed opcodes for INC, DEC, and ADC. Implemented various LD & LDH opcodes.
Set proper flags in INC, DEC, and SUB.
Completed CP opcode.
Completed ADD opcode.
Added a few LD opcodes.
Began memory map implementation.
Added push, pop, and a few RET-related opcodes.
Added debug code and cartridge RAM flag to MBC1.