Convert some of the functions to new format

Also, fix a lot of issues that appeared after the previous commits.

torch/optim/optimizer.py

@@ -134,6 +134,7 @@ class Optimizer(object):
             for param in group['params']:
                 if param.grad is not None:
                     param.grad.data.zero_()
+                    param.grad.detach_()
 
     def step(self, closure):
         """Performs a single optimization step (parameter update).