UAVOHoTTBridge: update flight mode strings
UAVOHoTTBridge: optimized climbrate calculation

Change climb rate buffer from float to int16_t type by using mm/0.2s as
unit. This saves 100 bytes of RAM.
Merge pull request #1345 from ernieift/ernieift/HoTT

UAVOHoTTBridge: update flight mode strings