Don't rely on object property order to sort tags

It works, but in theory it's not guaranteed in JS.
Show colored tags in tag selector in all views

Always show colored tags at the top of the tag selector, regardless of
whether they're in the current scope. If not, they're shown with reduced
opacity (as an equivalent to the gray style for out-of-scope tags in
Display All Tags mode). As a corollary, colored tags are now shown even
if they have no associated items and will remain until they're
explicitly deleted.

Also:

- Don't show outline on out-of-scope tags in "Display All Tags" mode
Fix error on tag change without a selected item (from 1e59c5ab7)
Fix broken checkboxes in tag selector context menu (OS X only?)

On OS X, the checked state of <menuitem type="checkbox"/> still doesn't
work right if set before the menu is opened. To get around this, the
state is now set manually in onpopupshown(). There's an annoying delay
before the UI update, but this is better than nothing.
Keep tag selector label heights consistent

Use a transparent border so that the height is the same with or without
zotero-clicky being set
Fix tag selector glitch after removing last tag, again

Better fix than 4e1fbf9747