editor: Add word count plugin to RichEditor toolbar

* This is useful when the input field has a character limit, allowing users to see the current character count.
* Related to inveniosoftware/invenio-requests#391

Author: Samk13

src/lib/forms/RichEditor.js

@@ -16,6 +16,7 @@ import "tinymce/plugins/autoresize";
 import "tinymce/plugins/codesample";
 import "tinymce/plugins/link";
 import "tinymce/plugins/lists";
+import "tinymce/plugins/wordcount";
 import PropTypes from "prop-types";
 
 export class RichEditor extends Component {
@@ -38,10 +39,10 @@ export class RichEditor extends Component {
       statusbar: false,
       min_height: minHeight,
       content_style: "body { font-size: 14px; }",
-      plugins: ["codesample", "link", "lists", "table", "autoresize"],
+      plugins: ["codesample", "link", "lists", "table", "autoresize", "wordcount"],
       contextmenu: false,
       toolbar:
-        "blocks | bold italic link codesample blockquote table | bullist numlist | outdent indent | undo redo",
+        "blocks | bold italic link codesample blockquote table | bullist numlist | outdent indent | wordcount | undo redo",
       autoresize_bottom_margin: 20,
       block_formats: "Paragraph=p; Header 1=h1; Header 2=h2; Header 3=h3",
       table_advtab: false,