Automatically apply new default map layers on update

[Glodenox]

There are some aerial imagery sources that do not have a "latest map" layer available. For those, I tend to add new layers to the corresponding map, but any existing maps will not automatically apply these new defaults. It would be best to copy over the default values whenever a map gets updated.

Possible approaches:

• Use existing structure: look at currently configured map layers and determine whether new ones have been added. Update the layers to the default layers if the new layer is part of the default layers.
• Map versioning: by adding versions to the map, it would be possible to notice whenever a new version is released and when an update of the default values may need to take place
• Map updated flags in releases: if we know which maps have been updated in a release, we could use that information to check whether any of their default values has to be adjusted

[Glodenox]

Alternative approach variant of option 1: adjust the visible map layer if it was the default one and another has now become the default one. It would require storing some sort of indication that the map layer configuration has remained untouched though.

Options 2 and 3 wouldn't have sufficient information to decide on what to do.

Either way, the logic is being changed that if no old map layers exist, a fresh map with the new default layers will be created, instead of the current logic where all new layers are added, but not made visible. The current logic almost always requires the removal and addition of the map layer again, as configuring the layers yourself is just annoying.