Copter: use the new scheduler load_average() call

this also simplifies the main loop

ArduCopter/ArduCopter.pde

@@ -954,12 +954,14 @@ void loop()
 
         // tell the scheduler one tick has passed
         scheduler.tick();
-    } else {
-        uint16_t dt = timer - fast_loopTimer;
-        if (dt < 10000) {
-            uint16_t time_to_next_loop = 10000 - dt;
-            scheduler.run(time_to_next_loop);
-        }
+
+        // run all the tasks that are due to run. Note that we only
+        // have to call this once per loop, as the tasks are scheduled
+        // in multiples of the main loop tick. So if they don't run on
+        // the first call to the scheduler they won't run on a later
+        // call until scheduler.tick() is called again
+        uint32_t time_available = (timer + 10000) - micros();
+        scheduler.run(time_available - 500);
     }
 }
 

ArduCopter/GCS_Mavlink.pde

@@ -199,7 +199,7 @@ static NOINLINE void send_extended_status1(mavlink_channel_t chan, uint16_t pack
         control_sensors_present,
         control_sensors_enabled,
         control_sensors_health,
-        0, // CPU Load not supported in AC yet
+        (uint16_t)(scheduler.load_average(10000) * 1000),
         battery_voltage1 * 1000, // mV
         battery_current,        // in 10mA units
         battery_remaining,      // in %