Initial implementation for Issue#2249.

Includes changes to sequence diagram code to enable popup menus and individualized styling of actors
Includes unit and e2e tests.
Includes updates to the md file for sequencediagrams.

src/defaultConfig.js

@@ -329,6 +329,17 @@ const config = {
      */
     mirrorActors: true,
 
+    /**
+     *| Parameter | Description |Type | Required | Values|
+     *| --- | --- | --- | --- | --- |
+     *| forceMenus | forces actor popup menus to always be visible (to support E2E testing). | Boolean| Required | True, False |
+     *
+     * **Notes:**
+     * 
+     * Default value: false.
+     */
+    forceMenus: false,
+
     /**
      *| Parameter | Description |Type | Required | Values|
      *| --- | --- | --- | --- | --- |