Add F.diagonal to reference
Add F.diagonal to reference

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