Feature - Allow sorting of albums by date of included photos.

[m-reiter]

Added the options to sort albums by date of their newest or oldest photo.

If this actually works, it should fix #1087 and #1123 and be a partial solution for #558.

This is my first PR, so apologies if I did anything wrong here - I'll be happy to learn and correct.

[m-reiter]

@pulsejet I don't want to rush but do you already have an idea whether you'll find time to look at this in the foreseeable future? If there's anything you don't like about it, it would be good to know and maybe try fixing while my memory is still fresh. Thanks!

[pulsejet]

I'm a bit concerned about the performance impact of this. The query needs to be studied carefully for effects on large albums (folks are running this with millions)

[m-reiter]

Thanks for looking! If I can do anything to help, let me know.

[fherreror]

Why not add a Date field to album description, manually filled by the user. In this way, it would not have to make a query for each album every time. It would sort all albums by their manually filled description date.
Just an idea. I think this feature would be great and I think this could be an intermediate solution