Converted fixed-size integer types to generic types for better portability.
Modified tests to cover multiple timers.

Adjusted mock system to scale to several timers, each with their own set
of settings. System interfaces changed to require an ID for the timer to
configure. Replaced system function calls in tests and driver code
accordingly.
Added rule in Makefile and pattern in gitignore for ctags file.
Converted Seconds arg to regular int.

Converted the numSecs argument for SetTimerCycleTimeSec from a short int
to a regular int. This allows the CycleTimeOverflow test to check the
overflow detection on all platforms.
Updated Trinket sample system header to match latest timer driver. Sample confirmed to operate correctly on hardware.
Added required system interfaces to Doxygen documentation.
Added ELF and HEX files to gitignore.