better printing for MPS

[starsfordummies]

now that we have forms and all that, it would be nice to have it shown when we print an mps. We could print also the info on the bond dimension (see #181 ) , maybe on the physical dimension as well

linkdims(psi) = [size(psi,link) for link in inds(psi, set=:inner)]
maxlinkdim(psi) = maximum(linkdims(psi))
function Base.show(io::IO, tn::T) where {T<:Tenet.AbstractQuantum}
               return print(io, "$T (inputs=$(nsites(tn; set=:inputs)), outputs=$(nsites(tn; set=:outputs))), chimax=$(maxlinkdim(tn)), form=$(form(psi))")
               end

julia> psi = rand(MPS, n=10, maxdim=128)
julia> psi
MPS (inputs=0, outputs=10), chimax=32, form=MixedCanonical(1)

Ideally even printing linkdims(psi) (so the bond dimension on all tensors) would be useful, but right now if I just print them like this it returns it in sparse ordering, which I don't like (should sort it appropriately but I'm not too sure how )

julia> psi = rand(MPS, n=10, maxdim=128)
MPS (inputs=0, outputs=10), chimax=32, form=MixedCanonical(1)

julia> print(linkdims(psi))
[2, 2, 16, 8, 4, 8, 16, 4, 32]

[mofeing]

I like the idea of prettier printing for MPS, MPO and other types in general.

About printing all the physical and virtual dimensions is not sth that I'm convinced because it will be big when we have a lot sites. But we should have sth like the following working:

size.(Ref(tn), inds(tn; set=:physical))
size.(Ref(tn), inds(tn; set=:virtual))

# or
size(tn; set=:physical)
size(tn; set=:bonds)

In general, the printing should just provide superficial info in a short message. But I agree that additional info should be easy to query.