Improvements and fixes

Ticket notices now go only to the people a ticket concerns. A deleted API token now produces a notice, and two-factor sign-in no longer breaks off while another browser tab is open.

• A new ticket now notifies only the person it is assigned to and anyone CC'd or mentioned, not everyone who can see the plant.
• Ticket notices now reach members and guests by email too, and can be switched off in the profile's "Notifications" tab.
• A mention in a ticket always produces a notice, even when ticket notifications are switched off.
• A notice now reports the deletion of one of the account's API tokens, naming the token and where the deletion came from.
• In the profile, a device using the Mirox app no longer shows as offline, and one on the latest version reads "Up to date".
• Two-factor sign-in no longer breaks off when another browser tab is open.