Non-standard shape convention for user-facing code

[mhubii]

The NVDiffRastRenderer generates BxHxWxC, which somewhat goes against the common PyTorch BxCxHxW convention:

roboreg/roboreg/core/rendering.py

Line 7 in dc3d1e3

class NVDiffRastRenderer:

This should be resolved, along with consequential unsqueeze and permute calls.