New implementation of PX4 RC Calibration

- Separated out RC Calibration into it's own Widget instead of being part of Vehicle Config code
- Added comprehensive unit test
- FYI: Copy Attitude Trims is temporarily disabled. You have to go through full calibration sequence to set trims. I will fix this in my next rev.
- UI uses new more modeless "Wizard" approach with the ability to Skip and Cancel at appropriate points. No more message boxes. Try Again for function mapping and inversion detection coming in Rev 2. 
- Channel widgets always display live data even when not calibrating
- Channel widgets which do not have an active rc channel are now disabled, with disabled draw for widget just showing border
- Previous implementation would end up with missing channels in the ui if you assigned attitude functions to any channel other than 1-4. Now all channels are displayed on the right always.
- You are no longer allowed to assign a channel to more than one function.

Lot's of other fixes and things along the way. I also have a long list of items for Rev 2 of RC Cal and also to work my way through all vehicle config screens to make them consistent and tested with automation.

Tested through the unit test, manual testing and PX4FMU firmware not complaining about bad RC cal values.