Potential bug detected for high-dimension real NVP

[kfzyqin]

I found the backflow of real NVP cannot reconstruct the original input data. This is caused by a bug in code when the dimension is more than 2:

pytorch-normalizing-flows/nflib/flows.py

Line 108 in b60e119

x0, x1 = x[:,::2], x[:,1::2]

pytorch-normalizing-flows/nflib/flows.py

Line 122 in b60e119

z0, z1 = z[:,::2], z[:,1::2]

They should be:

x0, x1 = x[:, :self.half_dim], x[:, self.half_dim:]
z0, z1 = z[:, :self.half_dim], z[:, self.half_dim:]

[janosh]

See #1.