Add Table class and use it in ItemArray

Table is a bi-dimensional version of Array

Use Kokkos::SubView to access rows and columns of Tables which are Array's

Do not use SubArray (to be removed) anymore to get a partial views of an Array, but Kokkos::SubView. The reason for this change is that SubArray were not a safe construction since the underlying Array could be destroyed (or resized) while the SubArray was still active. This has obviously an extra cost, but Kokkos developers have made the mechanism so that reference counters are deactivated (for all Kokkos::View) during parallel_for. Thus performances are the same but this new approach is safer. [Now one use the subArray() function to get a View on a part of an Array.]