Copter: move get_wp_xxx declarations higher in Copter.h

The declarations are grouped by the file in which they appear except for these 3

ArduCopter/Copter.h

@@ -673,6 +673,9 @@ private:
     void update_super_simple_bearing(bool force_update);
     void read_AHRS(void);
     void update_altitude();
+    bool get_wp_distance_m(float &distance) const override;
+    bool get_wp_bearing_deg(float &bearing) const override;
+    bool get_wp_crosstrack_error_m(float &xtrack_error) const override;
 
     // Attitude.cpp
     void update_throttle_hover();
@@ -914,11 +917,6 @@ private:
     void userhook_auxSwitch2(const RC_Channel::AuxSwitchPos ch_flag);
     void userhook_auxSwitch3(const RC_Channel::AuxSwitchPos ch_flag);
 
-    // vehicle specific waypoint info helpers
-    bool get_wp_distance_m(float &distance) const override;
-    bool get_wp_bearing_deg(float &bearing) const override;
-    bool get_wp_crosstrack_error_m(float &xtrack_error) const override;
-
 #if MODE_ACRO_ENABLED == ENABLED
 #if FRAME_CONFIG == HELI_FRAME
     ModeAcro_Heli mode_acro;