Changes

[Master]

Added converter for torch.Tensor.expand
Added support for custom converters for methods defined outside of torch module
Added names for TensorRT layers
Added GroupNorm plugin which internally uses PyTorch aten::group_norm
Replaced Tensor.ndim references with len(tensor.shape) to support older pytorch versions
Added reduced precision documentation page
Added converters for floordiv, mod, ne, and torch.tensor operations
Extended relu converter to support Tensor.relu operation
Extended sigmoid converter to support Tensor.sigmoid operation