support CartesianIndices as axes for TileIterator

[johnnychen94]

Currently, the axes argument only accepts tuple of ranges, and eltype of TileIteration is a tuple of ranges.

A = rand(200, 50);

R = TileIterator(axes(A), (128,8))
A[R[1]...]

It can be convenient to accept CartesianIndices here and make the eltype be CartesianIndices so that following usage is possible:

R = TileIterator(CartesianIndices(A), (128,8))
A[R[1]]

[timholy]

I haven't thought through all the implications but this seems quite logical. We might not have had CartesianIndices when this package was created, not sure.

[johnnychen94]

It's a bit ugly to display this if using #27:

julia> R = TiledIndices(CartesianIndices((15, 10)), (5, 5))
3×2 TiledIndices{2, Int64, CartesianIndices{1, Tuple{Base.OneTo{Int64}}}}:
 CartesianIndex{2}[CartesianIndex(1, 1) CartesianIndex(1, 2) … CartesianIndex(1, 5) CartesianIndex(1, 6); CartesianIndex(2, 1) CartesianIndex(2, 2) … CartesianIndex(2, 5) CartesianIndex(2, 6); … ; CartesianIndex(5, 1) CartesianIndex(5, 2) … CartesianIndex(5, 5) CartesianIndex(5, 6); CartesianIndex(6, 1) CartesianIndex(6, 2) … CartesianIndex(6, 5) CartesianIndex(6, 6)]                  …  CartesianIndex{2}[CartesianIndex(1, 6) CartesianIndex(1, 7) … CartesianIndex(1, 9) CartesianIndex(1, 10); CartesianIndex(2, 6) CartesianIndex(2, 7) … CartesianIndex(2, 9) CartesianIndex(2, 10); … ; CartesianIndex(5, 6) CartesianIndex(5, 7) … CartesianIndex(5, 9) CartesianIndex(5, 10); CartesianIndex(6, 6) CartesianIndex(6, 7) … CartesianIndex(6, 9) CartesianIndex(6, 10)]
 CartesianIndex{2}[CartesianIndex(6, 1) CartesianIndex(6, 2) … CartesianIndex(6, 5) CartesianIndex(6, 6); CartesianIndex(7, 1) CartesianIndex(7, 2) … CartesianIndex(7, 5) CartesianIndex(7, 6); … ; CartesianIndex(10, 1) CartesianIndex(10, 2) … CartesianIndex(10, 5) CartesianIndex(10, 6); CartesianIndex(11, 1) CartesianIndex(11, 2) … CartesianIndex(11, 5) CartesianIndex(11, 6)]             CartesianIndex{2}[CartesianIndex(6, 6) CartesianIndex(6, 7) … CartesianIndex(6, 9) CartesianIndex(6, 10); CartesianIndex(7, 6) CartesianIndex(7, 7) … CartesianIndex(7, 9) CartesianIndex(7, 10); … ; CartesianIndex(10, 6) CartesianIndex(10, 7) … CartesianIndex(10, 9) CartesianIndex(10, 10); CartesianIndex(11, 6) CartesianIndex(11, 7) … CartesianIndex(11, 9) CartesianIndex(11, 10)]
 CartesianIndex{2}[CartesianIndex(11, 1) CartesianIndex(11, 2) … CartesianIndex(11, 5) CartesianIndex(11, 6); CartesianIndex(12, 1) CartesianIndex(12, 2) … CartesianIndex(12, 5) CartesianIndex(12, 6); … ; CartesianIndex(14, 1) CartesianIndex(14, 2) … CartesianIndex(14, 5) CartesianIndex(14, 6); CartesianIndex(15, 1) CartesianIndex(15, 2) … CartesianIndex(15, 5) CartesianIndex(15, 6)]     CartesianIndex{2}[CartesianIndex(11, 6) CartesianIndex(11, 7) … CartesianIndex(11, 9) CartesianIndex(11, 10); CartesianIndex(12, 6) CartesianIndex(12, 7) … CartesianIndex(12, 9) CartesianIndex(12, 10); … ; CartesianIndex(14, 6) CartesianIndex(14, 7) … CartesianIndex(14, 9) CartesianIndex(14, 10); CartesianIndex(15, 6) CartesianIndex(15, 7) … CartesianIndex(15, 9) CartesianIndex(15, 10)]

Perhaps a good reason to simplify how CartesianIndices is displayed? CartesianIndex(1, 1):CartesianIndex(6, 6) maybe?