Test framework

[brabo]

Buildup a testing framework ASAP.

[maksymko]

One thing I was doing to test my changes, is to basically override MMIO32() macro, changing it to a function call, which and then verifying that the correct registers are accessed and correct values are set.

However, because I'm running the code on my machine (not the MCU), I find it much easier to implement this in C++, with all the standard library goodness.

I'll try to prepare a quick proof of concept, let me know what you think.