add distance measurements in cm

As per the discusison in
#310

the existing message struct contains distance
measurements specified to be in meters, which
is incorrect. Users who are currently accessing
this API are receiving the measurements in
centimeters.

protos/telemetry/telemetry.proto

@@ -739,9 +739,12 @@ message Odometry {
 
 // DistanceSensor message type.
 message DistanceSensor {
-    float minimum_distance_m = 1 [(mavsdk.options.default_value)="NaN"]; // Minimum distance the sensor can measure, NaN if unknown.
-    float maximum_distance_m = 2 [(mavsdk.options.default_value)="NaN"]; // Maximum distance the sensor can measure, NaN if unknown.
-    float current_distance_m = 3 [(mavsdk.options.default_value)="NaN"]; // Current distance reading, NaN if unknown.
+    float minimum_distance_m = 1 [(mavsdk.options.default_value)="NaN"]; // OBSOLETE: This was a typo in the naming.
+    float maximum_distance_m = 2 [(mavsdk.options.default_value)="NaN"]; // OBSOLETE: This was a typo in the naming.
+    float current_distance_m = 3 [(mavsdk.options.default_value)="NaN"]; // OBSOLETE: This was a typo in the naming.
+    float minimum_distance_cm = 1 [(mavsdk.options.default_value)="NaN"]; // Minimum distance the sensor can measure, NaN if unknown.
+    float maximum_distance_cm = 2 [(mavsdk.options.default_value)="NaN"]; // Maximum distance the sensor can measure, NaN if unknown.
+    float current_distance_cm = 3 [(mavsdk.options.default_value)="NaN"]; // Current distance reading, NaN if unknown.
 }
 
 // Scaled Pressure message type.

protos/telemetry_server/telemetry_server.proto

@@ -391,9 +391,12 @@ message Odometry {
 
 // DistanceSensor message type.
 message DistanceSensor {
-    float minimum_distance_m = 1 [(mavsdk.options.default_value)="NaN"]; // Minimum distance the sensor can measure, NaN if unknown.
-    float maximum_distance_m = 2 [(mavsdk.options.default_value)="NaN"]; // Maximum distance the sensor can measure, NaN if unknown.
-    float current_distance_m = 3 [(mavsdk.options.default_value)="NaN"]; // Current distance reading, NaN if unknown.
+    float minimum_distance_m = 1 [(mavsdk.options.default_value)="NaN"]; // OBSOLETE: This was a typo in the naming.
+    float maximum_distance_m = 2 [(mavsdk.options.default_value)="NaN"]; // OBSOLETE: This was a typo in the naming.
+    float current_distance_m = 3 [(mavsdk.options.default_value)="NaN"]; // OBSOLETE: This was a typo in the naming.
+    float minimum_distance_cm = 1 [(mavsdk.options.default_value)="NaN"]; // Minimum distance the sensor can measure, NaN if unknown.
+    float maximum_distance_cm = 2 [(mavsdk.options.default_value)="NaN"]; // Maximum distance the sensor can measure, NaN if unknown.
+    float current_distance_cm = 3 [(mavsdk.options.default_value)="NaN"]; // Current distance reading, NaN if unknown.
 }
 
 // Scaled Pressure message type.