* Generate api docs from source code
* Add a bunch of doxygen comments
* more doxygen comments
* Add the in-progress api docs
* script to generate docs from travis
* Add doc generation to the travis job
* make travis_docs.sh commit the work it does
* make sure the docs script exits cleanly
Adopt the macros for saving/restoring the interrupt state
that are provided by the avr gcc environment.
Removing intialization of the timer value; this shaves off
a few bytes because globals are default initialized to zero.
