pairwise for arrays of arrays

[theogf]

It would be nice to be able to be able to deal with arrays of arrays as well.
For example :

A = [rand(3) for _ in 1:3]
P = pairwise(SqEuclidean(),A)
# Where pairwise(SqEuclidean(),hcat(A,...),dims=2) == P

In this case one could of course simply concatenate vectors, but for more complex objects (not necessarily real vectors) that would broaden the use of pairwise!
I could make a PR if you think that makes sense

[mkborregaard]

And please also Iterators and generators :-)

[yakir12]

+1 this would also allow for collections of StaticVectors (as in, coordinates).