Type the datasets, and the minibatch

[paraynaud]

mutable struct KnetNLPModel{T, S, C <: Chain, V} <: AbstractKnetNLPModel{T, S}
  meta::NLPModelMeta{T, S}
  chain::C
  counters::Counters
  data_train
  data_test
  size_minibatch::Int
  minibatch_train
  minibatch_test
  current_minibatch_training
  current_minibatch_testing
  w::S
  layers_g::Vector{Param}
  nested_array::V
end

We must try to type data_train, data_test, minibatch_train, minibatch_test, current_minibatch_training, current_minibatch_testing