Trim usernames

Previously it was possible to "impersonate" (to those not looking closely) other users by putting whitespace before or after the name of choice. This commit eliminates that.

src/WSServer.ts

@@ -527,6 +527,7 @@ export default class WSServer {
         if (!newName) {
             client.assignGuestName(this.getUsernameList());
         } else {
+            newName = newName.trim();
             if (hadName && newName === oldname) {
                 //@ts-ignore
                 client.sendMsg(guacutils.encode("rename", "0", "0", client.username, client.rank));