couple of bug fixes
1. more generic test for ATMEGA168/328 to reset the watchdog
2. mini-mwc with internal-rx should use cppm order = TAER*
3. rearranged the interrupt handlers for serialrx_cppm. for the cppm interrupt handler:

= use the ICP version for
- atmega168/328 AND seiralrx_cppm AND !(mini-mwc and internal-rx) (PB0)

= use the NON-ICP version for
- atmega168/328 AND seiralrx_cppm AND (mini-mwc and internal-rx) (PD2)
- nano-wii (PE6)