Minor fixes + SBUS dynamic RX

Hope I structured this right, Kenny… Let me know if the SBUS stuff is
totally wrong, I'm not quite sure what you're doing since AQ32 and MEGA
are done quite differently.

Altitude hold throttle adjust fix - constraining wasn't happening at
the right times, if zDampening was enabled, the change in throttle
could be 2x min/maxThrottleAdjust.
Merge pull request #404 from imchipwood/development

Minor fixes + SBUS dynamic RX