On me head son

I'm throwing huge lumps of code into the repository at the moment.  I got the first pass at the instruction emulation in and am now writing and executing unit tests.  I've already found and fixed a whole bunch of problems, especially in my condition code flag calculations.

Hooray for unit tests !

It is also incredibly satisfying to watch the tests complete successfully or to follow the operations step by step and see the instructions actually doing the right thing :-)