Add PROTOCOL_VERSION and friends to minimal.xml (mavlink#1178)

message_definitions/v1.0/minimal.xml

@@ -381,6 +381,14 @@
         <description>Component for handling system messages (e.g. to ARM, takeoff, etc.).</description>
       </entry>
     </enum>
+    <enum name="MAV_CMD">
+      <description>Commands to be executed by the MAV. They can be executed on user request, or as part of a mission script. If the action is used in a mission, the parameter mapping to the waypoint/mission message is as follows: Param 1, Param 2, Param 3, Param 4, X: Param 5, Y:Param 6, Z:Param 7. This command list is similar what ARINC 424 is for commercial aircraft: A data format how to interpret waypoint/mission data. See https://mavlink.io/en/guide/xml_schema.html#MAV_CMD for information about the structure of the MAV_CMD entries</description>
+      <entry value="519" name="MAV_CMD_REQUEST_PROTOCOL_VERSION" hasLocation="false" isDestination="false">
+        <description>Request MAVLink protocol version compatibility</description>
+        <param index="1" label="Protocol">1: Request supported protocol versions by all nodes on the network</param>
+        <param index="2">Reserved (all remaining params)</param>
+      </entry>
+    </enum>
   </enums>
   <messages>
     <message id="0" name="HEARTBEAT">
@@ -392,5 +400,15 @@
       <field type="uint8_t" name="system_status" enum="MAV_STATE">System status flag.</field>
       <field type="uint8_t_mavlink_version" name="mavlink_version">MAVLink version, not writable by user, gets added by protocol because of magic data type: uint8_t_mavlink_version</field>
     </message>
+    <message id="300" name="PROTOCOL_VERSION">
+      <wip/>
+      <!-- This message is work-in-progress and it can therefore change. It should NOT be used in stable production environments. -->
+      <description>Version and capability of protocol version. This message is the response to REQUEST_PROTOCOL_VERSION and is used as part of the handshaking to establish which MAVLink version should be used on the network. Every node should respond to REQUEST_PROTOCOL_VERSION to enable the handshaking. Library implementers should consider adding this into the default decoding state machine to allow the protocol core to respond directly.</description>
+      <field type="uint16_t" name="version">Currently active MAVLink version number * 100: v1.0 is 100, v2.0 is 200, etc.</field>
+      <field type="uint16_t" name="min_version">Minimum MAVLink version supported</field>
+      <field type="uint16_t" name="max_version">Maximum MAVLink version supported (set to the same value as version by default)</field>
+      <field type="uint8_t[8]" name="spec_version_hash">The first 8 bytes (not characters printed in hex!) of the git hash.</field>
+      <field type="uint8_t[8]" name="library_version_hash">The first 8 bytes (not characters printed in hex!) of the git hash.</field>
+    </message>
   </messages>
 </mavlink>