Move the generation of indices used for iterating over broadcasted tensors to _generate_broadcasting_indices

Added more explicit error message when trying to use verify_grad on something with more than one output

Fixed recent buggy implementation of CrossentropySoftmax1HotWithBiasDx.grad and added unit test to check it

Also gived info on how to give name to variables.

bugfix in gpu convolution on the gpu. The bug as created in revision f57050592a51 the 26 january 2010.