External ADC pad support for rssi and power meter

Allowing use of ADC_CHANNEL5 for rssi (rssi_adc_channel) and power meter
(power_adc_channel) on external pad (Rev5 only)
Missed correct number of places power adc comment
Removed unnecessary defaulting to 0

Defaulting to 0 isn't needed as the struct is memset()'d anyway.
Redo sbus scaling/offset calculation based on data from FrSky X4R and d91ba93b8400ea118cd6fca1012c0ed2da14e3b7.
Removed sbus_offset as it's not needed with this. Closes #48
Fix for softserial code.
Merge pull request #191 from CurtisFissel/master

Fix for softserial code.
Update mw.h

Addition of Model: ATail4 basically tail is mounted inverted to VTail4
Addition of Model: ATail4 basically tail is mounted inverted to VTail4
Addition of Model: ATail4 basically tail is mounted inverted to VTail4

Addition of Model: ATail4 basically tail is mounted inverted to VTail4
  Addition of Model: ATail4 basically tail is mounted inverted to VTail4
Addition of Model: ATail4 basically tail is mounted inverted to VTail4
Addition of Model: ATail4 basically tail is mounted inverted to VTail4
Merge pull request #192 from norem/master

Addition of Model: ATail4 basically tail is mounted inverted to VTail4
Fix MAG_NONE and ACC_NONE cases
Merge pull request #197 from DTFUHF/mag_none_fix

Fix MAG_NONE and ACC_NONE cases
Initial merge of PatrikE's Fixed Wing RTH
Merge pull request #198 from readerror67/fw-nav

Initial merge of PatrikE's Fixed Wing RTH
Renaming fixed wing parameters per cTn's request.
Ooops, removed the extra _FW.
Remove un-used stuff, Keil now has no warnings.