Instruction decode rewrite
Registers $8 and up are now back in action

After a longer hiatus of only having a 3-bit wide register select signal
for 16 registers, the select signal is now 4-bit wide.

Much rejoice was had in the lands.
Inrease sram memory size to accomodate 512*256 FB
Add helpful debug prints
Add SLT&MASK and Square draw system tests. Passing.