Yes, a more modular layout, albeit the fact that this is still but one
single source file. However, this reorganization will better
facilitate breaking this up into module files.
* Convert to C.
* Add simavr test/debug code.
* Fix/improve 1-second timer pin.
* Do not modify lastSerClock in clearState().
* Add pin change interrupt for serial clock, sleep during serial clock
edges, build out PCINT0 ISR to handle watching for multiple pin
changes on the same ISR.
The code compiles, but there is NO GUARANTEE it is actually functional.
The code still needs to be tested and could use a bit of careful reading
code review to certify that it does not contain errors.
