Commander: Switch into right mode in various corner conditions

* If you move in LAND, AUTO or HOLD the sticks the system will give control back to the pilot
  * If you do not connect any RC the system will default to HOLD and will allow you tablet control
  * If you gain position lock for the first time the system will re-evaluate the mode switch (so if you dropped down to alt hold it will now go into position)
  * If the system breaches the Geofence it will now always drop back to POSCTRL if the sticks are moved

src/modules/commander/commander_params.c

@@ -178,6 +178,21 @@ PARAM_DEFINE_FLOAT(COM_EF_TIME, 10.0f);
  */
 PARAM_DEFINE_FLOAT(COM_RC_LOSS_T, 0.5f);
 
+/**
+ * RC stick override threshold
+ *
+ * If an RC stick is moved more than by this amount the system will interpret this as
+ * override request by the pilot.
+ *
+ * @group Commander
+ # @unit %
+ * @min 5
+ * @max 40
+ * @decimal 0
+ * @increment 0.05
+ */
+PARAM_DEFINE_FLOAT(COM_RC_STICK_OV, 12.0f);
+
 /**
  * Home set horizontal threshold
  *