Copter: add trapezoid frame type

We still need to properly define the motor mixing for the trapezoid
frame in AP_MotorsQuad.cpp

libraries/AP_Motors/AP_MotorsQuad.cpp

@@ -23,6 +23,12 @@ void AP_MotorsQuad::setup_motors()
         add_motor(AP_MOTORS_MOT_2, -90, AP_MOTORS_MATRIX_MOTOR_CCW, 4);
         add_motor(AP_MOTORS_MOT_3,   0, AP_MOTORS_MATRIX_MOTOR_CW,  1);
         add_motor(AP_MOTORS_MOT_4, 180, AP_MOTORS_MATRIX_MOTOR_CW,  3);
+    }else if( _frame_orientation == AP_MOTORS_TRAPEZOID_FRAME ) {
+        // To-Do correct motor mixing properly for trapezoidal frame
+        add_motor(AP_MOTORS_MOT_1,   45, AP_MOTORS_MATRIX_MOTOR_CCW, 1);
+        add_motor(AP_MOTORS_MOT_2, -135, AP_MOTORS_MATRIX_MOTOR_CCW, 3);
+        add_motor(AP_MOTORS_MOT_3,  -45, AP_MOTORS_MATRIX_MOTOR_CW,  4);
+        add_motor(AP_MOTORS_MOT_4,  135, AP_MOTORS_MATRIX_MOTOR_CW,  2);
     }else{
         // X frame set-up
         add_motor(AP_MOTORS_MOT_1,   45, AP_MOTORS_MATRIX_MOTOR_CCW, 1);

libraries/AP_Motors/AP_Motors_Class.h

@@ -32,9 +32,10 @@
 #define AP_MOTORS_APM2  2
 
 // frame definitions
-#define AP_MOTORS_PLUS_FRAME 0
-#define AP_MOTORS_X_FRAME 1
-#define AP_MOTORS_V_FRAME 2
+#define AP_MOTORS_PLUS_FRAME        0
+#define AP_MOTORS_X_FRAME           1
+#define AP_MOTORS_V_FRAME           2
+#define AP_MOTORS_TRAPEZOID_FRAME   3
 
 // motor update rate
 #define AP_MOTORS_SPEED_DEFAULT 490