Scripting: Added tiled.load to load assets without opening an editor

[bjorn]

Still WIP, has known issues are likely also undiscovered ones.

Intended as a solution for #3517.

[justgook]

maybe you can list issues? so some-one could fix / test those?

[bjorn]

@justgook Ha, indeed, listing the ones I apparently knew about would have been good for myself as well. I even forgot I already had a patch in progress for this at some point. First step now would be to rebase this and test it.

[bjorn]

I've rebased it and gave it a quick test. Appears to work fine, but one noticeable issue is present on exit, it prints:

TilesetManager: There are still 3 tilesets loaded at exit!

This indicates tileset references are still alive when they shouldn't be. I don't get this message on the master branch.

[justgook]

just gut filling - that you have forgot to transfer ownership:

if (auto document = TilesetDocument::findDocumentForTileset(tileset->sharedFromThis()))
         return new EditableTileset(document);

     editable = new EditableTileset(tileset);
     editable->moveOwnershipToCpp();

or something in that area - so you left with tilesets that is not own by anyone

so it is still loaded, and "not closed" properly.

PS. not tested - just from own exp what that could be.
PSS. im not big expert in C++ - just gut filling from 20+ years exp in web dev.