Immediately remove unread tag from one-message threads

[po1vo]

If 'auto_remove_unread' is enabled, immediately remove unread tag from one-message threads.

[lucc]

Hi @po1vo is there a reason you closed #1582 and moved that commit here? It looks like these are two unrelated things, so it might be easier to discuss them in two PRs. Should we reopen #1582 or remove the help window commit entirely? (Or are they in fact related, then I don't get why.)

For the unread stuff: I see what you do, but can you explain why this is needed?

[po1vo]

Hi @po1vo is there a reason you closed #1582 and moved that commit here? It looks like these are two unrelated things, so it might be easier to discuss them in two PRs.

Sorry for the mess, i committed to the wrong branch. Regarding #1582, i realized my solution could be better since i found that notify() from alot/ui.py relies on escape key as well.

For the unread stuff: I see what you do, but can you explain why this is needed?

It's just annoying to have to navigate within an email body to have alot mark a single email read. I realize it was done this way to wait until a user actually navigates to an unread email within a thread, but for single-email threads that's totally unnecessary.