Bugfix: Module Builder Create from Existing Table - Maintenance Fields

Module Builder

Bugfix when creating module from existing table
- MB would add View table columns for Deleted, Created, Modified when
these would already have been displayed as part of the normal column
names (from existing table)

Added
- Hidden form field containing name of 'deleted' column
(for consistency with other fields and to remove hard-coded values)

- mb_form_match_existing entry in all builder_lang.php files
- display of mb_form_match_existing to modulebuilder_form.php
- show() and hide() of mb_form_match_existing to modulebuilder.js