Metadata should be sorted to better support diff’ing

[matthias-ronge]

The metadata is stored in Kitodo in a random order. This is correct, as metadata is without any explicit order in MODS. However, when two file versions are compared by the programmer (with “diff”), there are many changes, and these are not changes, but they are caused due to the random order of entries.

Goal: is to save the metadata in sorted order, by name, and then by value Edit: metadata of the same name should keep their order across several saves (see below). Since the order is meaningless, it can also be stored this way.

[matthias-ronge]

There are circumstances in which it is expressly desired that metadata of the same name have a fixed order. This applies to contributors, for example. Thus, while an alphabetical ordering of metadata by name would be desirable, metadata within the same name should simply retain their manually established (or random) order across multiple saves.