AP_ServoRelayEvents: add static create method

libraries/AP_ServoRelayEvents/AP_ServoRelayEvents.h

@@ -11,16 +11,15 @@
 
 class AP_ServoRelayEvents {
 public:
-    AP_ServoRelayEvents(AP_Relay &_relay) : 
-    relay(_relay),
-    mask(0),
-    type(EVENT_TYPE_RELAY),
-    start_time_ms(0),
-    delay_ms(0),
-    repeat(0),
-    channel(0),
-    servo_value(0)
-    {}
+    static AP_ServoRelayEvents create(AP_Relay &_relay) {
+        return AP_ServoRelayEvents{_relay};
+    }
+
+    constexpr AP_ServoRelayEvents(AP_ServoRelayEvents &&other) = default;
+
+    /* Do not allow copies */
+    AP_ServoRelayEvents(const AP_ServoRelayEvents &other) = delete;
+    AP_ServoRelayEvents &operator=(const AP_ServoRelayEvents&) = delete;
 
     // set allowed servo channel mask
     void set_channel_mask(uint16_t _mask) { mask = _mask; }
@@ -32,6 +31,18 @@ public:
     void update_events(void);
 
 private:
+    AP_ServoRelayEvents(AP_Relay &_relay)
+        : relay(_relay)
+        , mask(0)
+        , type(EVENT_TYPE_RELAY)
+        , start_time_ms(0)
+        , delay_ms(0)
+        , repeat(0)
+        , channel(0)
+        , servo_value(0)
+    {
+    }
+
     AP_Relay &relay;
     uint16_t mask;