reworked the exercise edit dialog. Moved javascript part from editor_edit.js.erb to exercises.js.erb.

Manipulated some further javascript as necessary. It is not super elegant, but this is due to the former structure of the code which uses cloned dummy forms.
Integrating the ace editor made some strange calls necessary.
Also fixed toggling the input area and the file upload dialog

app/assets/stylesheets/editor.css.scss

@@ -7,6 +7,16 @@ button i.fa-spin {
   width: 100%;
 }
 
+/* this class is used for the edit view of an exercise. It needs the height set, as it does not automatically resize */
+.edit-frame {
+  height: 400px;
+
+  audio, img, video {
+    max-width: 100%;
+  }
+}
+
+
 .frame {
   display: none;