Use new 0.7 interface for QR and co?

[Datseris]

In current version 0.7.1 of StaticArrays something like e.g.

s = SMatrix{4,4}(rand(4,4))
qr(s)

returns a tuple of (Q, R). Should this be updated to reflect the new approach followed by Base LinearAlgebra?

ps in addition there of course the well-known deprecation warnings from using Base instead of LinearAlgebra

[c42f]

This has been done and we now return a factorization object from qr.