Change model assumptions

[Floppy]

At the moment we assume that any folder with a 3d file in is a model; subfolders are also models. This assumption should probably be changed to something like:

• The library root cannot be a model - files here are ignored.
• Any folder containing scannable files, including its subfolders, should be a single model.

Does that seems like a more sensible default?

[ksuquix]

That makes sense to me... I'm already a good bit down the path of getting this finished (although I've had some interruptions at the day job).

I was also thinking of flags of minimum/maximum depth for recognition of a model.
E.G. If my general organization scheme is: creator/collection/model and I am very strict with that, I could theoretically put a min of 3 and a max of 3 to recognize anything at the "model" level as a model.

Then if I had a model that consisted of two subdirectories "supported" and "unsupported", it would still parse as a model if I had it at that level.

[Floppy]

I've made some changes in #1300 that automatically include subfolders like "supported" and "unsupported". Might just be an interim fix before we make bigger changes, but I think it's a step forward.