🚑 Quickfix incorrectly connected LeakyReLU in residual block

Patches c2f3ec2. Residual block was not constructed properly, as we used uppercase 'X' instead of lowercase 'x' inside the python function. That means the generator network's parameter counts have changed again...

Only retrained twice to test if this fixed residual block performs better. This commit specifically references experiment at https://www.comet.ml/weiji14/deepbedmap/497bd90c68d74aaa97a63818161b3897. The RMSE_test metric is slightly above 100, similar to the best result before, but perhaps less prone to exploding/vanishing gradients? Visual inspection of results in deepbedmap.ipynb does look better than previous run though.