AP_Baro: add static create method

libraries/AP_Baro/AP_Baro.h

@@ -24,8 +24,13 @@ class AP_Baro
     friend class AP_Baro_SITL; // for access to sensors[]
 
 public:
-    // constructor
-    AP_Baro();
+    static AP_Baro create() { return AP_Baro{}; }
+
+    constexpr AP_Baro(AP_Baro &&other) = default;
+
+    /* Do not allow copies */
+    AP_Baro(const AP_Baro &other) = delete;
+    AP_Baro &operator=(const AP_Baro&) = delete;
 
     // barometer types
     typedef enum {
@@ -159,8 +164,10 @@ public:
 
     // set a pressure correction from AP_TempCalibration
     void set_pressure_correction(uint8_t instance, float p_correction);
-    
+
 private:
+    AP_Baro();
+
     // how many drivers do we have?
     uint8_t _num_drivers;
     AP_Baro_Backend *drivers[BARO_MAX_DRIVERS];