A few CSS discrepancies and fixes

[duck_]

When opening a menu item for editing in Chrome (and Safari), Opera or (probably) KHTML based browser, the bottom left and right corners stay rounded this is because the CSS styles don't redefine these corners only the top ones again (note haven't explicitly tested Safari or Konqueror).

Also fixes the red appearance of a menu item handle when it is deleted (accidentally removed in r14337).

[duck_]

Adding a few more general CSS changes to this ticket rather than opening another ticket.

[duck_]

image for RTL classic favourite actions dropdown

[duck_]

3 RTL changes: fix the arrow image on the favourite actions dropdown when using classic theme; remove the indent triangle from the admin menu; and fix position of tag input background text. (NB: only tested with RTL but still English, though don't really see how this would affect my testing)

Finally fix background for tabs on theme page when using classic theme.

[nacin]

(In [14795]) Various CSS fixes for nav menus and RTL. props duck_, fixes #13441.

[nacin]

(In [14796]) Script loader bump, and revert new orange that snuck in. see #13441.

[nacin]

(In [14798]) One more RTL tweak. props duck_, fixes #13441.