PLT-3101 Added message history (#3205)

* Added message history

* Minor logical changes

* Fixed indexes resetting

* Fixed double messages

* Fixed resetting main history when RHS opened

webapp/components/edit_post_modal.jsx

@@ -9,6 +9,7 @@ import * as GlobalActions from 'actions/global_actions.jsx';
 import Textbox from './textbox.jsx';
 import BrowserStore from 'stores/browser_store.jsx';
 import PostStore from 'stores/post_store.jsx';
+import MessageHistoryStore from 'stores/message_history_store.jsx';
 import PreferenceStore from 'stores/preference_store.jsx';
 
 import Constants from 'utils/constants.jsx';
@@ -49,6 +50,8 @@ class EditPostModal extends React.Component {
             return;
         }
 
+        MessageHistoryStore.storeMessageInHistory(updatedPost.message);
+
         if (updatedPost.message.length === 0) {
             var tempState = this.state;
             Reflect.deleteProperty(tempState, 'editText');