Added mini-batch training to the encoder-decoder benchmark.
Added mini-batch training to the encoder-decoder benchmark.

marian-nmt/marian-train,emjotde/amunn,marian-nmt/marian-train,DianaDespa/marian-train,amunmt/marian,marian-nmt/marian-train,DianaDespa/marian-train,emjotde/amunn,DianaDespa/marian-train,amunmt/marian,DianaDespa/marian-train,emjotde/amunn,afaji/Marian,amunmt/marian,emjotde/Marian,afaji/Marian,emjotde/amunmt,emjotde/amunmt,emjotde/amunmt,marian-nmt/marian-train,DianaDespa/marian-train,emjotde/amunn,emjotde/Marian,marian-nmt/marian-train,emjotde/amunmt,afaji/Marian,afaji/Marian