msp430: remove expensive modulo call
msp430: show overflow counter in hwtimer debug
msp430: cc430: handle hwtimer interrupts correctly

TAIFG should count the overflows, instead of using the first CCR for this purpose.
Without this commit ARCH_MAXTIMERS returns the wrong number as
effectively one timer less can be used.

Additional fixed comment style and added timer debug.
test_hwtimer: hwtimer is automatically initialized now
msp430: don't enable Timer 0 by default
Initial import of low-level PWM driver interface
Fixed spelling
drivers: small fixes for low-level pwm driver IF

- added UNDEFINED device for compatability
- adjusted meaning of return values for init and set functions
- overdue spell fix
ccnl: remove dead code
Update README.md
Merge pull request #937 from mehlis/ccnl-dead-code

ccnl: remove dead code
Merge pull request #941 from LudwigOrtmann/native_invocation

Update README.md
Merge pull request #615 from haukepetersen/periph_driver_pwm

Initial import of low-level PWM driver interface
Merge pull request #909 from OlegHahm/msp430_hwtimer

msp430: hwtimer: handle overflow correctly