Configurable message list actions

The Problem

I use K-9 as well as mail clients on a PC. Generally I do two things with K-9: check new mail and sort spam. The actions I mostly use are: mark as read/unread (or star), mark as spam/ham, rarely delete. The actions that are available at the top of the screen in the folder view after marking (long-pressing) messages are: delete, mark read/unread, archive, (and move on horizontal screens) don't match my workflow. The former two are available in the message view. I'd really prefer to have a spam/ham button instead of delete or archive.

Another place where quickly available actions don't match my routines are notifications. I'd prefer having spam/ham button instead of delete here too.

Possible solution

Make the order of actions fully configurable, so every one can customize the set of actions they have available as buttons/icons to match their own needs in all three contexts: the message list, the message view, and the notifications.

Additional context

Having #1793 implemented would also help me sort my spam/ham.

P.S. Thanks for the great new 5.800. It looks great and works like charm.

No source files or tests are named. Start by tracing the action buttons in the message list, message view, and notifications, and review the related context in #1793. Done means users can configure the order and set of available actions independently across all three contexts.