making conv_layer a .cu file so that it's compiled with nvcc and can include .cuh headers that have templates
setting up template includes
setting up template includes
more expressive CUDA_CHECK macro... tells you the error.
gpu forward conv mockup. segfaults (unspecified launch error)... probably needs some fixes in the indexing.
if we put a really tight guard on the x,y,f that get to run on GPU, the segfault goes away. going to do some printfs and hunt down the bug soon