GitLab

* wip: layer normalization on cpu

* wip: add cuda implementation, nor working yet

* wip: try to fix cuda implementation

* swap grid_strid_range and grid_strid_range_y: does not work yet

* fix CUDA implementation

* implement cuda gradient

* add documentation, move layer_norm, update bn_visitor

* add tests

* use stddev instead of variance in test (they are both 1, anyway)

* add test for means and invstds on CPU and CUDA

* rename visitor to disable_duplicative_bias

* handle more cases in the visitor_disable_input_bias

* Add tests for visitor_disable_input_bias