Noise ignored in denoising VAE

[sunsided]

This PR handles #56 by replacing

if denoising:
    current_input = utils.corrupt(x) * corrupt_prob + x * (1 - corrupt_prob)

# 2d -> 4d if convolution
x_tensor = utils.to_tensor(x) if convolutional else x
current_input = x_tensor

with

# apply noise if denoising
x_ = (utils.corrupt(x) * corrupt_prob + x * (1 - corrupt_prob)) if denoising else x

# 2d -> 4d if convolution
x_tensor = utils.to_tensor(x_) if convolutional else x_
current_input = x_tensor

The temporary x_ was introduced to keep the original input x intact for the loss function.

[pkmital]

Nice one! Thank you!