added feature where Conv3D ops give names to their gradients

fixed a bug in ConvTransp3D where infer_shape transposes two of the axes

Add yet another option for how to run the check_whitespace hook: incremental-with-patch. The idea is: If a file was clean, block commits that make it unclean. If it wasn't clean, don't block, but still propose a patch to clean it up. This may not work for folks using an hg gui. Thanks to Fred for the suggestion.

Removed some unneeded cleanup code left over from previous attempts to fix the segfault-on-exit problem.

Fixed BLAS compilation instructions under Windows to be more coherent with other Windows instructions