Support of NamedTuples

[xukai92]

trafficstars

This should be supported.

dataset = (x=rand(10), y=rand(2, 10))
for batch in eachbatch(dataset; size=3)
    # do something with batch.x and batch.y
end

[oxinabox]

This is a significant part of https://github.com/JuliaML/MLDataUtils.jl/issues/46

Since a named tuple of vectos is a valid Tables.jl ColumnTable

So solving this would make big steps towards Tables.jl compat.

[oxinabox]

As a short term workaround if you load MLDataUtils, DataFrames support will be loaded, and then you can do:

dataset = (x=rand(10), y=rand(2, 10))
df = DataFrame(dataset)
for batch in eachbatch(df; size=3)
    # do something with batch.x and batch.y
end