Added supervisor/user mode support and a test for it, everything works as intended. Still need to write the unit test for branch-if-CO.

Added conditional branch support and a test for it. Currently only have a test for the branch-if-Z path, not the branch-if-CO path. Next step will be to add a unit test for branch-if-CO, then probably work on fault/trap/interrupt support.

Added support for ALU status bits Z (last operation result was zero) and OC (overflow/carry out) and tests for them. Also added add8.ab which adds lower bytes of registers A and B. Next step will be to add conditional branch […]

Wrote a new unit test system, and implemented tests for all current instructions. Next step will probably be to look at implementation of ALU status bits, so we can do branching in the future.