Incorporate review comments:

1) Line up trailing dimensions in broadcast docs.
2) remove unnecessary expand_as in common_nn test.
3) use view in tensor_str instead of resize_.
4) newExpand remove raiseErrors change.
5) clarify expandedSizes/expandedStrides parameters in inferExpandGeometry.
6) simplify inferSize2/inferSizeN implementations.
7) use new-style classes for warning.
4 files changed