Variables need to managed properly for renaming/deletion

Right now our variable management is rather sloppy. We need to a couple of things here.

- Variables that are specific to nodecomment should be prefixed with "node_comment_". Right now we've got a couple like "comment_view_$type" and "comment_plural_$type" that are not prefixed correctly, but others that are.
- Variables are not renamed or deleted with a node type is deleted. We need to implement hook_node_type() and accomidate for changes to node types.
- Variables are not deleted on module uninstall.