Separate out traits into Core/Base package?

[rayegun]

Hi there.

I'm keen to use ArrayLayouts in some upcoming sparse ecosystem stuff. Not so much for the generic linalg but just for the traits.

In light of that would it be possible/make sense to split out the traits into their own base package? That way I can use the traits without adding an unrelated dependency.

Without realizing ArrayLayouts existed I had started with just Col and Row major in StorageOrder.jl (almost nothing there currently though).