tests: colorize output
oldland-test: wait for debug socket to be active.

Rather than a sleep of 1 second, wait for initialization so we can run
tests a little quicker.
debugger: close socket on termination.
soc: default instruction data to a NOP.

Until we have errors being generated on instruction fetch make sure that
we reset to having a sensible value otherwise we'll come out of reset
into the invalid instruction handler.
cpu: implement illegal instruction exception.

Execution of an illegal instruction now raises an exception.