4051 Select All option on tag edit page over-ambitious

https://code.google.com/p/otwarchive/issues/detail?id=4051

Using the All button on tag edit pages was selecting way more tags than it should. Specifically, it was selecting all the tags in the parent fieldset, and not just the tags it's related to. Now we're filtering the checkboxes using an attribute, like we do on tag set pages. 

I changed it from a plain made-up attribute (checkbox_name_filter) to an HTML5 data attribute (data-checkbox-id-filter) so it will validate in the future, even though it doesn't validate right now (the previous form didn't validate, either). Also, I made it check the filter against the checkbox's id attribute rather than its name attribute, since that will work both on the tag edit page and tag sets page (so the attribute has been appropriately renamed id-filter rather than name-filter).
I know this is just a comment, but should it say "[...] to match on the id field of the checkboxes"? This will show if I understood what it does at all. *g*