PadMessageHandler: Delete unnecessary `protocolVersion`

We can assume that the client code is always in sync with what the
server expects.

src/node/handler/PadMessageHandler.js

@@ -813,17 +813,6 @@ const handleClientReady = async (socket, message, authorID) => {
     return;
   }
 
-  if (!message.protocolVersion) {
-    messageLogger.warn('Dropped message, CLIENT_READY Message has no protocolVersion!');
-    return;
-  }
-
-  if (message.protocolVersion !== 2) {
-    messageLogger.warn('Dropped message, CLIENT_READY Message has a unknown protocolVersion ' +
-                       `'${message.protocolVersion}'!`);
-    return;
-  }
-
   await hooks.aCallAll('clientReady', message);
 
   // Get ro/rw id:s

src/node/handler/SocketIORouter.js

@@ -69,10 +69,6 @@ exports.setSocketIO = (_io) => {
     }
 
     socket.on('message', (message, ack = () => {}) => {
-      if (message.protocolVersion && message.protocolVersion !== 2) {
-        logger.warn(`Protocolversion header is not correct: ${JSON.stringify(message)}`);
-        return;
-      }
       if (!message.component || !components[message.component]) {
         logger.error(`Can't route the message: ${JSON.stringify(message)}`);
         return;

src/static/js/pad.js

@@ -202,7 +202,6 @@ const sendClientReady = (isReconnect) => {
     padId,
     sessionID: Cookies.get('sessionID'),
     token,
-    protocolVersion: 2,
   };
 
   // this is a reconnect, lets tell the server our revisionnumber

src/static/js/timeslider.js

@@ -102,7 +102,6 @@ const sendSocketMsg = (type, data) => {
     padId,
     token,
     sessionID: Cookies.get('sessionID'),
-    protocolVersion: 2,
   });
 };
 

src/tests/backend/specs/socketio.js

@@ -86,7 +86,6 @@ const handshake = async (socket, padID) => {
     padId: padID,
     sessionID: null,
     token: 't.12345',
-    protocolVersion: 2,
   });
   logger.debug('waiting for CLIENT_VARS response...');
   const msg = await getSocketEvent(socket, 'message');
@@ -464,7 +463,6 @@ describe(__filename, function () {
       let serverSocket;
       const want = {
         component: this.test.fullTitle(),
-        protocolVersion: 2,
         foo: {bar: 'asdf'},
       };
       let rx;
@@ -482,7 +480,6 @@ describe(__filename, function () {
     });
 
     const tx = async (socket, message = {}) => await new Promise((resolve, reject) => {
-      message = Object.assign({protocolVersion: 2}, message);
       const AckErr = class extends Error {
         constructor(name, ...args) { super(...args); this.name = name; }
       };