generated doxygen config and documented ZumoBuzzer
rewrote ZumoBuzzer documentation examples to use instantiated object
merge in QTR sensors lib 2.1.1
ZumoBuzzer doc minor fix/add
add include guard to ZumoReflectanceSensorArray.h
added QTRSensors docs and started ZumoReflectanceSensorArray
continuing documentation

added brief descriptions to classes and stubbed unfinished stuff; changed
a few settings in Doxyfile to not repeat brief desc, inline inherited
members, and hide protected members (kind of hacky)
added readme for ZumoExamples to briefly explain its purpose
Added param and return documentation to ZumoBuzzer
ZumoReflectanceSensorArray documentation in progress
finished documenting ZumoReflectanceSensorArray
changed args to be specified with \a, which seems to make more sense semantically
README.textile: Add a link to the new repository for the Pushbutton library.
Merge branch 'master' of github.com:pololu/zumo-shield