Re-factored code to use the xf_forum table instead of xf_node so it only gets applied to forum nodes, not all nodes.
Added code into installer to remove old field in xf_node and create new field in xf_forum.
Note:
- You will need to re-edit any forum nodes you have already applied this to (sorry!)
- You can remove this file, it's no longer required: /library/NewThreadButtonText/DataWriter/Node.php