Remove "Automatically select next message" setting

I have seen it as an option in other clients but have personally never wanted to disable it. I think I'd want to get some wider feedback, though.

Just following up, some feedback I've received is that some people don't want images to automatically load because of tracking. This is solved by the setting to not load images automatically.

Another thing some have said is that they don't want images to be marked as read unless they actually have read them. That's probably a valid concern

Hi, really interesting point here, based on my personal experience using different clients I can say the following applies:

- When I delete an email, I found that I don't want the client to select the next immediate email by default, this is implying that the client knows what my next action will be, from a UX perspective this is not correct, which will also make the logic of deciding what's the next email to read either stupid or too complicated.
- Selecting the email should mark the email as read, e.g. Outlook will mark the email as read-only after an X number of seconds, which is a bit stressful, especially if it takes me less time to read/acknowledge an email.
- I'd like to have a way to apply the "inbox zero" policy to my inbox, where emails have four states: "actionable" (or pinned in Google Inbox terms), unread, archived, deleted, with a modality to display all pinned items with only one click.

Hope this helps.

For the time being, I use this setting as a workaround for a bug in Mail affecting very large emails (or very long threads of mails). I'd recommend not removing the feature completely until https://bugs.launchpad.net/pantheon-mail/+bug/1645790 is fixed.