improve axis detection
improve axis detection

instead of searching for an axis with value != zero, looks for a delta
of more than 10% in axis value. The reference value for each axis is
captured when the user clicks the button to set an axis

AlexanderDzhoganov/ksp-advanced-flybywire,agufranov/ksp-advanced-flybywire,agufranov/ksp-advanced-flybywire,taniwha/ksp-advanced-flybywire