Arduino Mega 2560: Add initialization code for LED
Arduino Mega 2560: add WIP of timer implementation, uses overflow interrupts,
should switch to compare interrupts (better match for channel logic)
[mod] switch timers to COMPA instead of overflow
Arduino Mega 2560: Add implementation of hwtimer_arch.c (identical to the one
from the aruino due)
Arduino Mega 2560: reduce default stacksizes
Arduino Mega 2560: clean up catchall-loop
Arduino Mega 2560: add WIP of task_switching logic
[mod] remove debugging printf from TIMER1_COMPA_vect