Use the `all_admin_notices` hook the switch back message
Correct the admin toolbar item IDs
Switch to the `login_init` hook for switching actions
Update plugin header
Tweak the redirect location for BuddyPress user profiles
Add some more query args to be removed when doing a redirect
Simplify some logic in `switch_to_user()` and `switch_off_user()`
Switch to storing data in cookies as JSON. Not backwards compatible, but non-breaking