Implement CHIP-8 Instructions: Bitwise Arithmetic

[fokoid]

• [x] 0x8XY1 Sets VX to VX or VY. (bitwise OR operation) (Vx |= Vy)
• [x] 0x8XY2 Sets VX to VX and VY. (bitwise AND operation) (Vx &= Vy)
• [x] 0x8XY3 Sets VX to VX xor VY. (Vx ^= Vy)
• [x] 0x8XY6 Stores the least significant bit of VX in VF and then shifts VX to the right by 1.[b] (Vx >>= 1)
• [x] 0x8XYE Stores the most significant bit of VX in VF and then shifts VX to the left by 1.[b] (Vx <<= 1)

Pseudocode and descriptions were sourced from the CHIP-8 Wikipedia article and are licensed under the Creative Commons Attribution-ShareAlike License 3.0.

[fokoid]

note: the bitshift operators vary in implementation. the original COSMAC interpreter set VX = VY before shifting; modern interpreters ignore VY entirely. adding a configuration object to the machine to tweak this, with the modern behaviour the default for now.