Implement `jump_quirks`

[craigthomas]

The --jump_quirks controls how jumps to various addresses are made with the jump (Bnnn) instruction. In the original Chip8 language specification, the jump is made by taking the contents of register 0, and adding it to the encoded numeric value, such as:

PC = V0 + nnn

With the Super Chip8 specification, the highest 4 bits of the instruction encode the register to use (Bxnn). The behavior of --jump_quirks becomes:

PC = Vx + nn