AP_Scripting: add arming-check-batt-temp example script

libraries/AP_Scripting/examples/arming-check-batt-temp .lua

@@ -0,0 +1,19 @@
+-- This script runs a custom arming check of the battery temperature
+
+auth_id = arming:get_aux_auth_id()
+batt_temp_max = 35
+
+function update() -- this is the loop which periodically runs
+  if auth_id then
+    now = millis()
+    batt_temp = battery:get_temperature(0)
+    if not batt_temp then
+      arming:set_aux_auth_failed(auth_id, "Could not retrieve battery temperature")
+    elseif (batt_temp >= batt_temp_max) then
+      arming:set_aux_auth_failed(auth_id, "Batt temp too high (" .. tostring(batt_temp) .. "C > " .. tostring(batt_temp_max) .. "C)")
+    end
+  end
+  return update, 5000 -- reschedules the loop in 5 seconds
+end
+
+return update() -- run immediately before starting to reschedule