WIP: static ranges for smarter macro comprehensions

[andyferris]

To address #26, we need some way of getting constant values in a comprehension like

function f{N}(::SomeType{N})
    ...
    vec = @SVector [2x for x = 1:N]
    ...
end

Here I play with new types StaticIndex{Idx,T} and the much simpler StaticOneTo{N}. The latter is hooked into the SVector macro to achieve the above. These ideas need generalizing and making robust, and I'd appreciate any opinions on how we might want to deal with statically valued arrays?

[andyferris]

any opinions on how we might want to deal with statically valued arrays?

E.g. Is statically-valued worth its own type tree like StaticArray, complete with many generic methods? What is the interface? Is it a trait?

@timholy @c42f

[c42f]

I think this is superseded by #150 ? Please reopen if I'm wrong!