Add button to manually mark all notifications as read

app/javascript/flavours/glitch/reducers/notifications.js

@@ -16,6 +16,7 @@ import {
   NOTIFICATIONS_DELETE_MARKED_FAIL,
   NOTIFICATIONS_ENTER_CLEARING_MODE,
   NOTIFICATIONS_MARK_ALL_FOR_DELETE,
+  NOTIFICATIONS_MARK_AS_READ,
 } from 'flavours/glitch/actions/notifications';
 import {
   ACCOUNT_BLOCK_SUCCESS,
@@ -297,6 +298,9 @@ export default function notifications(state = initialState, action) {
     }
     return markAllForDelete(st, action.yes);
 
+  case NOTIFICATIONS_MARK_AS_READ:
+    return recountUnread(state, state.get('items').first().get('id'));
+
   default:
     return state;
   }