* Previously, the ELEVON_REVERSE parameter was equivelant in function to the
  ELEVON_CH1_REVERSE parameter. These parameter values are found in
  g.reverse_elevons and g.reverse_ch1_elevon, and used to map to the radio_out
  channels in ArduPlane/Attitude.pde
* It seems the author's intent was for ELEVON_REVERSE to change the sign for
  the combination of pitch & roll into ch1 & ch2, as there are already
  parameters which change just the sign of ch1 and just the sign of ch2.
* Discovered this bug because I happened to build an elevon airframe which was
  not possible to setup with the existing ELEVON_ and RCn_REV parameters.
* This will break existing elevon setups if the user used ELEVON_REVERSE
  instead of ELEVON_CH1_REVERSE, since they were previously interchangable.