`isless` for Vector

[haampie]

We have lexicographical isless for several list types:

('a', 'b') < ('c', 'd') #true
"ab" < "cd" #true

yet we don't have it for Vector:

['a', 'b'] < ['c', 'd'] # ERROR: MethodError: no method matching isless(::Array{Char,1}, ::Array{Char,1})

From a mathematical point of view it might make sense not to have isless for vectors, but for general purpose it seems at least consistent to have it. If it's supported in Base, then so will it be in StaticArrays.jl, which is useful (JuliaArrays/StaticArrays.jl#367).

Thoughts?

[iblislin]

I prefer to have this feature in https://github.com/JuliaStats/Distances.jl

[haampie]

It's not entirely clear to me how distance and order are related; defining isless(x, y) = dist(x) < dist(y) doesn't produce a totally ordered set.

[JeffBezanson]

This is implemented on master.

[haampie]

That's great, sorry for the noise.