Issue: [4.1 Alpha 1] Categories: Add to/remove from page duplication and missing phrase

1) Using the AJAX edit categories overlay, when removing a category from a page it is sometimes (but not always) shown twice in the "remove categories" section. In the "current categories" section it remains but with two icons 'X+' (intended?). This means it is possible for one category to be displayed here three times in total. The 'X+' icons appears when removing categories while editing a page as well (?do=edit) but again, not sure if this was intended.

2) Missing phrase in flash message: #!-- XEN:VWPHRASE vw_page_categories_saved ARGS() --#


As a side discussion for something later down the line, I do wonder if there could be some visual tweaks here such as:

• Add category textbox & new category button (keep current)
• Categories to add (keep current, order moved up above existing categories)
• NEW: Form divider separating "Add categories" (above) and "Existing categories" (below)
• NEW: List of categories with checkbox toggle to remove (combine current/remove categories blocks)

For the last point I guess what I'm suggesting is just have existing categories in a selected/not selected for removal state like XenForo's inline moderation on posts etc, rather than the clickable X's and separated current/remove lists. And overall, the adjusted order/styling would I think better distinguish the two operations here (add & remove categories)