GitLab

* Add new loss for weighted pixel inputs (may be useful e.g. to emphasize rare classes)

* Deduplicate method loss_multiclass_log_per_pixel_(weighted_)::to_label

* Add a simple test case for weighted inputs
(also, fix a typo in test_tensor_resize_bilienar's name)

* Add loss_multiclass_log_per_pixel_weighted_ to loss_abstract.h

* Decrease the amount of weighting

* There's no need to train for a very long time