Add other versions of Wesnoth to the Load Game dialog

[stevecotton]

This has only been tested on Linux so far, I don't have the other OSes
to test on.

If a save directory from another version is found, a drop-down list of
directories is added below the filter box in the Load Game dialog.

Refactor save_index_class to allow instances for other directories.

Design idea: all new saves go in to the main save directory. Games can be
loaded from other directories, but those directories are treated as read-only.
When building an index for other directories, the index is kept in memory and
not written to disk - this results in some noticeable lag in the UI when opening
the other versions' directories, but not the usual save dir.

[nemaara]

Is it possible to move said button somewhere else? I feel like a less prominent place like the lower left might be better.

[stevecotton]

I'd like to keep it prominent, because part of the reason for adding this is to prevent 1.16.0 getting negative reviews that upgrading from 1.14 has made the old save games disappear.

I'm wondering about putting it on the same line as the filter, because there's some unused space there. It being part of the filter might work as a UI concept, because what it does is to show a subset of all available files.

[nemaara]

Well this goes back to the UI design stuff I was talking about the other day (which I really should put as an issue here sometime): since it takes up such a prominent position in the loading screen, you're essentially saying that the ability to load from other versions of wesnoth is just as important as the basic ability to search for/load saves.

I'm not doubting the usefulness this feature, and I also see your point about players being annoyed at not having their 1.14 saves transfer to 1.16 (some of them will not work on 1.16, regardless of whether they try to load from the 1.14 folder or not), but I don't think it's quite as important as being able to load saves at all. At the very least, I'd say moving it to below the dialog listing all the save names makes more sense to me.

[stevecotton]

Please could you link to the "UI design stuff"? I've looked at the last week's IRC logs but didn't find it.

Moving it on the search line looks good to me. For this dialog I find that I focus on the centre (so the file list and map preview), everything at the edges seems less important to me. The new button won't appear at all if the user doesn't have a save dir from another version.

I'd like to make the search box a bit wider so that the right hand side of the new button aligns with the right hand side of other objects - haven't worked out why setting a grow_factor isn't working.

[stevecotton]

I'd like to make the search box a bit wider so that the right hand side of the new button aligns with the right hand side of other objects - haven't worked out why setting a grow_factor isn't working.

Was missing a horizontal_grow = true, however having tried it I think that change doesn't look good.

[nemaara]

Hey, that looks better to me. Yes, having it off to the side makes it less prominent and now there's no gap between the filter and saves dialog, so that's good.

Edit: I put the UI design stuff here #4531.

[stevecotton]

I plan to merge this on Sunday morning (European time). I'd prefer to have feedback from non-Linux developers first, but if I don't get feedback on a Saturday then I assume that waiting longer won't help.

[CelticMinstrel]

I can't tell from this log whether this was merged or rejected?

[stevecotton]

It was merged, I think the reason that it doesn't show as merged is because I added a changelog when doing a manual rebase-and-merge.

Original merge: b66bdb8
Bugfixes for non-Linux (thanks to @shikadiqueen) : e15a611 and 666c4d2.