Give the user more control over forum viewing settings

Currently, each forum is always displayed by default as a List and with its threads being sorted by recent activity. Both of these can be changed from the "Sort & view" menu. However, I see two issues in the current form of doing things:

• These are only per-forum settings. The user has no way to change how the forums will look to them by default.

• These changes do not persist after Fluxer is closed. The user will have to keep changing the look of a forum every time they open the app, which is somewhat impractical.

I think it would be best if these two changes were made:

• Option for the user to change the default Sort & view settings

• Make the per-forum settings (which will count as exceptions to the default rule) persist across sessions