Add year, track number, custom sorting orders

[logchan]

This PR adds:

1. Year and track number display
2. Ability to sort by multiple columns

Every time the user changes sorting (asc -> dsc -> disable) of a column, it is lifted to the first in sorting order.

For example, to sort by year then by album then by track, click Track -> Album -> Year. This is the same logic as Foobar2000.

[martpie]

First off, great work!

If this behavior is familiar to foobar 2000 users, I see a couple of pitfalls:

• People that are not power-users may never truly understands how this system works
• It is less consistent with how a file explorer or other music players work (I have itunes in mind specifically)
• The most important point: I am struggling to understand what problem is it trying to solve? Did you have the need to do custom column sorting in the past?

Not dismissing the effort you put there, this is actually great work! I'm just trying to understand the usecase, and how needed it is by other users.

My focus with Museeks has always been:

You will not find tons of features, as its goals is not to compete with more complete and more famous music players.

So I'm always for sane defaults over crazy customization.

[logchan]

Good point about giving user sane defaults. I also agree that the current modifications would make the player less usable out-of-the-box for non power users. Ironically, I chose museeks because it is both simple in UI and have most of the features that I need (notably the library management, really smooth and well made).

The reason I'm adding the customized sort is that the default sort orders don't work very well in my case. In particular, I'd prefer sorting by track number after sorting by album, so an album would play in its original order, regardless of possible differences in artists (the default sorts by artists first). Certainly many would prefer that order, so I made it customizable.

While I don't think the feature of defining a sort order is "crazy", it does not have to be the only, or even default, option. To me it's now like finding a balance between simplicity (user friendliness) and feature rich - the current version is unnecessarily complicated for users, while the original, in my use case, cannot sort properly. So I'm proposing the following change:

• By default, sorting works as before (when a column is chosen, other columns sort in a predefined order).
• There is an "Advanced" panel in settings to enable custom sorts.
• It also has checkboxes of which columns are shown. And the defaults would have year and track numbers hidden. My use case here is to hide Genre since it's an empty column for my library.

At a high level, my point is to be open to adding some features that may be niches, but hiding them so they're not disturbing to general users and simplicity is kept.