Relax dimensionality requirements in `A*_mul_B*!` and `transpose!`

Conflicts:
	base/linalg/matmul.jl
More performant solution for transpose! with Vectors (see #8726)
Merge pull request #8821 from JuliaLang/teh/vecmat

Relaxed dimensionality requirements for various LinAlg operations (backport 0.3)