fix editorType to read correct element

In JFormFieldEditor, $editorType reads $element['editor'] instead of $element['editorType']

For BC, added a fallback to use 'editor' if 'editorType' is not provided as an attribute.

Tracker: http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=33257