[WIP] implementing col2im
[WIP] implementing col2im

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