fix(iframe_api): Change the format of the arguments in the constructor

doc/api.md

 ```javascript
 <script src="https://meet.jit.si/external_api.js"></script>
 ```
-
 ## API
 
-### `api = new JitsiMeetExternalAPI(domain, room, [width], [height], [htmlElement], [configOverwite], [interfaceConfigOverwrite], [noSsl], [jwt])`
+### `api = new JitsiMeetExternalAPI(domain, options)`
 
 The next step for embedding Jitsi Meet is to create the Jitsi Meet API object.
 Its constructor gets a number of options:
 
 * **domain**: domain used to build the conference URL, "meet.jit.si" for
   example.
-* **room**: name of the room to join.
-* **width**: (optional) width for the iframe which will be created.
-* **height**: (optional) height for the iframe which will be created.
-* **htmlElement**: (optional) HTL DOM Element where the iframe will be added as
-  a child.
-* **configOverwite**: (optional) JS object with overrides for options defined in
-  [config.js].
-* **interfaceConfigOverwrite**: (optional) JS object with overrides for options
-  defined in [interface_config.js].
-* **noSsl**: (optional, defaults to true) Boolean indicating if the server
-  should be contacted using HTTP or HTTPS.
-* **jwt**: (optional) [JWT](https://jwt.io/) token.
+* **options**: object with properties - the optional arguments:
+    * **room**: (optional) name of the room to join.
+    * **width**: (optional) width for the iframe which will be created.
+    * **height**: (optional) height for the iframe which will be created.
+    * **htmlElement**: (optional) HTL DOM Element where the iframe will be added as a child.
+    * **configOverwite**: (optional) JS object with overrides for options defined in [config.js].
+    * **interfaceConfigOverwrite**: (optional) JS object with overrides for options defined in [interface_config.js].
+    * **noSsl**: (optional, defaults to true) Boolean indicating if the server should be contacted using HTTP or HTTPS.
+    * **jwt**: (optional) [JWT](https://jwt.io/) token.
 
 Example:
 
 ```javascript
-var domain = "meet.jit.si";
-var room = "JitsiMeetAPIExample";
-var width = 700;
-var height = 700;
-var htmlElement = document.querySelector('#meet');
-var api = new JitsiMeetExternalAPI(domain, room, width, height, htmlElement);
+var options = {
+    domain: "meet.jit.si",
+    room: "JitsiMeetAPIExample",
+    width: 700,
+    height: 700,
+    htmlElement: document.querySelector('#meet')
+}
+var api = new JitsiMeetExternalAPI(domain, options);
 ```
 
 You can overwrite options set in [config.js] and [interface_config.js].
 For example, to enable the filmstrip-only interface mode, you can use:
 
 ```javascript
-var interfaceConfigOverwrite = {filmStripOnly: true};
-var api = new JitsiMeetExternalAPI(domain, room, width, height, undefined, undefined, interfaceConfigOverwrite);
+var options = {
+    interfaceConfigOverwrite: {filmStripOnly: true}
+};
+var api = new JitsiMeetExternalAPI(domain, options);
 ```
 
 You can also pass a jwt token to Jitsi Meet:
 
  ```javascript
-var jwt = "<jwt_token>";
-var noSsl = false;
-var api = new JitsiMeetExternalAPI(domain, room, width, height, htmlElement, configOverwrite, interfaceConfigOverwrite, noSsl, jwt);
+var options = {
+    jwt: "<jwt_token>",
+    noSsl: false
+};
+var api = new JitsiMeetExternalAPI(domain, options);
  ```
 
 ### Controlling the embedded Jitsi Meet Conference

modules/API/external/external_api.js

     return url;
 }
 
+/**
+ * Parses the arguments passed to the constructor. If the old format is used
+ * the function translates the arguments to the new format.
+ *
+ * @param {Array} args - The arguments to be parsed.
+ * @returns {Object} JS object with properties.
+ */
+function parseArguments(args) {
+    if (!args.length) {
+        return {};
+    }
+
+    const firstArg = args[0];
+
+    switch (typeof firstArg) {
+    case 'string': // old arguments format
+    case undefined: // eslint-disable-line no-case-declarations
+    // not sure which format but we are trying to parse the old
+    // format because if the new format is used everything will be undefined
+    // anyway.
+        const [
+            roomName,
+            width,
+            height,
+            parentNode,
+            configOverwrite,
+            interfaceConfigOverwrite,
+            noSSL,
+            jwt
+        ] = args;
+
+        return {
+            roomName,
+            width,
+            height,
+            parentNode,
+            configOverwrite,
+            interfaceConfigOverwrite,
+            noSSL,
+            jwt
+        };
+    case 'object': // new arguments format
+        return args[0];
+    default:
+        throw new Error('Can\'t parse the arguments!');
+    }
+}
+
 /**
  * The IFrame API interface class.
  */
      *
      * @param {string} domain - The domain name of the server that hosts the
      * conference.
-     * @param {string} [roomName] - The name of the room to join.
-     * @param {number} [width] - Width of the iframe.
-     * @param {number} [height] - Height of the iframe.
-     * @param {DOMElement} [parentNode] - The node that will contain the
+     * @param {Object} [options] - Optional arguments.
+     * @param {string} [options.roomName] - The name of the room to join.
+     * @param {number} [options.width] - Width of the iframe.
+     * @param {number} [options.height] - Height of the iframe.
+     * @param {DOMElement} [options.parentNode] - The node that will contain the
      * iframe.
-     * @param {Object} [configOverwrite] - Object containing configuration
-     * options defined in config.js to be overridden.
-     * @param {Object} [interfaceConfigOverwrite] - Object containing
+     * @param {Object} [options.configOverwrite] - Object containing
+     * configuration options defined in config.js to be overridden.
+     * @param {Object} [options.interfaceConfigOverwrite] - Object containing
      * configuration options defined in interface_config.js to be overridden.
-     * @param {boolean} [noSSL] - If the value is true https won't be used.
-     * @param {string} [jwt] - The JWT token if needed by jitsi-meet for
+     * @param {boolean} [options.noSSL] - If the value is true https won't be
+     * used.
+     * @param {string} [options.jwt] - The JWT token if needed by jitsi-meet for
      * authentication.
      */
-    constructor(domain, // eslint-disable-line max-params
-        roomName = '',
-        width = MIN_WIDTH,
-        height = MIN_HEIGHT,
-        parentNode = document.body,
-        configOverwrite = {},
-        interfaceConfigOverwrite = {},
-        noSSL = false,
-        jwt = undefined) {
+    constructor(domain, ...args) {
         super();
+        const {
+            roomName = '',
+            width = MIN_WIDTH,
+            height = MIN_HEIGHT,
+            parentNode = document.body,
+            configOverwrite = {},
+            interfaceConfigOverwrite = {},
+            noSSL = false,
+            jwt = undefined
+        } = parseArguments(args);
+
         this._parentNode = parentNode;
         this._url = generateURL(domain, {
             configOverwrite,