StaticArray results and input

[tpapp]

Allow versions of transformations that return StaticArrays.

Roadmap:

1. include size information in types
2. SMatrix, SVector, and possibly MMatrix and MVector versions of UnitVector and CorrCholeskyFactor, maybe specified with the {} in the constructor, also include size there?
3. Array aggregator should also allow this, maybe with as(SVector{size}, ...) syntax? Possibly a unified syntax for both static and plain vanilla arrays.
4. Tuple and NamedTuple aggregators can probably be untouched, caching dimensions information could just lead to (minor) speedups.

Bikeshedding syntax/API is most welcome.