Allow mixed dtypes in concatenate arguments
Allow mixed dtypes in concatenate arguments

hvy/chainer,okuta/chainer,keisuke-umezawa/chainer,niboshi/chainer,wkentaro/chainer,chainer/chainer,okuta/chainer,chainer/chainer,keisuke-umezawa/chainer,okuta/chainer,chainer/chainer,tkerola/chainer,pfnet/chainer,hvy/chainer,wkentaro/chainer,keisuke-umezawa/chainer,niboshi/chainer,wkentaro/chainer,hvy/chainer,keisuke-umezawa/chainer,wkentaro/chainer,hvy/chainer,niboshi/chainer,niboshi/chainer,okuta/chainer,chainer/chainer