crazyflie: fix PWM channel ordering

Channels belonging to a certain timer were not all grouped together.
This is required by the .first_channel_index and .last_channel_index data
members.

We introduce a new mixer geometry to solve the problem.

src/lib/mixer/MultirotorMixer/CMakeLists.txt

@@ -48,6 +48,7 @@ set(geometry_files
 	quad_s250aq.toml
 	quad_vtail.toml
 	quad_wide.toml
+	quad_x_cw.toml
 	quad_x.toml
 	quad_x_pusher.toml
 	quad_y.toml

src/lib/mixer/MultirotorMixer/geometries/quad_x_cw.toml

@@ -0,0 +1,30 @@
+# Generic Quadcopter in X configuration
+# with clock-wise motor numbering
+
+[info]
+key = "4xcw"
+description =  "Quadcopter in X configuration with clock-wise motor numbering"
+
+[rotor_default]
+direction = "CW"
+axis      = [0.0, 0.0, -1.0]
+Ct        = 1.0
+Cm        = 0.05
+
+[[rotors]]
+name      = "front_right"
+position  = [0.707107, 0.707107, 0.0]
+direction = "CCW"
+
+[[rotors]]
+name     = "rear_right"
+position = [-0.707107, 0.707107, 0.0]
+
+[[rotors]]
+name      = "rear_left"
+position  = [-0.707107, -0.707107, 0.0]
+direction = "CCW"
+
+[[rotors]]
+name     = "front_left"
+position = [0.707107, -0.707107, 0.0]