Category/tag converter should support all public taxonomies

[sillybean]

The category to tag converter should let you convert terms to custom taxonomies, if any are defined. I'm attaching a rewrite of the plugin based on 1.5.2, which included support for post formats.

What it looks like with some of my test taxonomies

Added a couple of checks to exclude nav menus

Awesome. Will be testing out later, needed to do some thorough testing of the post format stuff and look over that todo list again anyway. (P.S. stolen my idea :P)

Would be nice if the hierarchy was preserved when converting from one hierarchical taxonomy to another.

That would also put some pressure on the taxonomy caching bugs, such as #14485

Finally, I would like to suggest an alternative UI: adding a new bulk action to wp-admin/edit-tags.php.

I've taken this approach in the ​Term Management Tools plugin.

Hmm, could preserve the parents if they're also being converted, I suppose. I'll take a look later.

I'm conflicted on the bulk edit idea. It would be simpler, but... too simple, maybe, for something that isn't an everyday operation.

Posting here so I don't lose it: ​bug report from forum testers.