ATC_HOVR_ROL_TRM Is giving out of range warning on heli when set to negative

In copter heli ATC_HOVR_ROL_TRM can be set positive or negative depending on the mechanics of the airframe. Mission planner gives out of range warnings if you set this parameter to a negative value to have the heli roll to the left.

Mission Planner 1.3.83 build 1.3.9454.39344

Set ATC_HOVR_ROL_TRM to negative value.

Our of range "ATC_HOVR_ROL_TRM value is out of range. Do you want to continue?" warning pops up and must be accepted to set a negative value.

Negative values are normal and to be expected for some traditional helicopter configurations.

Start by reproducing the warning in Mission Planner 1.3.83 while setting ATC_HOVR_ROL_TRM to a negative value, then trace the parameter range validation used by the parameter-setting workflow. Done means valid negative values for this helicopter parameter can be set without the out-of-range warning, while invalid values remain guarded.

Written by the indexing model from the issue text.