Add an optional warning before tagging armor with special slots

[jondthompson]

When I'm working through clearing my armor or just tagging in general, I'm not thinking about special slots, so it is possible that I may mark something to be deleted that I don't mean to. It would be useful in particular for anything that has a special slot to put a popup on the screen saying that I just tagged something for deletion that has a special slot, and do I want to undo that tagging? (when tagging, I filter by untagged often, so undoing an unintended tag can interfere with the process.)