Modularize Makefile
PS/2 decoder
Add some warning flags
Keyboard driver
Simplify prop_PS2State_Rep
Add type signature
Use Hardware.KansasLava.PS2
Code reorganization
Chip8-specific keyboard driver
First semi-working version of Chip8 CPU
Fix scancode for 'W' key
Implement WaitKey state
Fix stopping condition of Draw state
appendS seems to have weird semantics re. argument order...
Fix intialization of Draw and ClearFB states
Include font ROM
Fix keyboard layout
Fix stack handling
For saving/restoring registers, the opcode contains the max reg number, not the value in the register
Increment PC and go to Fetch1 after addPtr