Dots in displaying views of sparse/structured arrays

[jishnub]

With this, views of sparse/structured arrays are printed with dots as well:

julia> D = Diagonal(1:4)
4×4 Diagonal{Int64, UnitRange{Int64}}:
 1  ⋅  ⋅  ⋅
 ⋅  2  ⋅  ⋅
 ⋅  ⋅  3  ⋅
 ⋅  ⋅  ⋅  4

julia> view(D, 1:3, 1:3)
3×3 view(::Diagonal{Int64, UnitRange{Int64}}, 1:3, 1:3) with eltype Int64:
 1  ⋅  ⋅
 ⋅  2  ⋅
 ⋅  ⋅  3

julia> S = sparse([1,2,2,2,3], [1,1,2,2,4], [5, -19, 73, 12, -7])
3×4 SparseMatrixCSC{Int64, Int64} with 4 stored entries:
   5   ⋅  ⋅   ⋅
 -19  85  ⋅   ⋅
   ⋅   ⋅  ⋅  -7

julia> view(S, 1:3, 1:3)
3×3 view(::SparseMatrixCSC{Int64, Int64}, 1:3, 1:3) with eltype Int64:
   5   ⋅  ⋅
 -19  85  ⋅
   ⋅   ⋅  ⋅

[stevengj]

LGTM. Could use a NEWS item?

[jishnub]

Which header should the news entry be added under? "New language features"?

[ViralBShah]

Usually LinearAlgebra has a section in NEWS.

[jishnub]

Strictly speaking, this isn't a LinearAlgebra change, but a Base subarray one. I suppose most of the applications are in linear algebra, so including it in that section would make sense

[KristofferC]

Feels a bit excessive with a NEWS item for this. I think it can just be merged.