mavproxy_mode: use MAV_CMD_DO_REPOSITION for 'Fly To'

this has the advantage that you don't need to be in guided mode to start the command.  Prevents some clunky interactions between pilot and GCS operator as the vehicle does not need to be somewhere safe to loiter before the command can be safely issued.

MAVProxy/mavproxy.py

@@ -267,6 +267,7 @@ def __init__(self):
               MPSetting('rallyalt', int, 90, 'Default Rally Altitude', range=(0,10000), increment=1),
               MPSetting('terrainalt', str, 'Auto', 'Use terrain altitudes', choice=['Auto','True','False']),
               MPSetting('guidedalt', int, 100, 'Default "Fly To" Altitude', range=(0,10000), increment=1),
+              MPSetting('guided_use_reposition', bool, True, 'Use MAV_CMD_DO_REPOSITION for guided fly-to'),
               MPSetting('rally_breakalt', int, 40, 'Default Rally Break Altitude', range=(0,10000), increment=1),
               MPSetting('rally_flags', int, 0, 'Default Rally Flags', range=(0,10000), increment=1),
 

MAVProxy/modules/mavproxy_mode.py

@@ -84,6 +84,25 @@ def cmd_guided(self, args):
             altitude = float(args[0])
 
         print("Guided %s %s" % (str(latlon), str(altitude)))
+
+        if self.settings.guided_use_reposition:
+            self.master.mav.command_int_send(
+                self.settings.target_system,
+                self.settings.target_component,
+                self.module('wp').get_default_frame(),
+                mavutil.mavlink.MAV_CMD_DO_REPOSITION,
+                0,  # current
+                0,  # autocontinue
+                -1,   # p1 - ground speed, -1 is use-default
+                mavutil.mavlink.MAV_DO_REPOSITION_FLAGS_CHANGE_MODE,   # p2 - flags
+                0,   # p3 - loiter radius for Planes, 0 is ignored
+                0,   # p4 - yaw - 0 is loiter clockwise
+                int(latlon[0]*1.0e7),
+                int(latlon[1]*1.0e7),
+                altitude
+            )
+            return
+
         self.master.mav.mission_item_int_send(
             self.settings.target_system,
             self.settings.target_component,