BUG FIX - MaterialBase - from_tensor: Exclude normal maps from normalization

[bearprin]

Avoiding the normal normalization when initializing the material from the torch tensor
(Normal should always be [-1, 1] for normal when rendering)

This is already processed for the 'as_tensor' function, but the 'from_tensor' function does not handle that

[giuvecchio]

Hi @bearprin, thanks for pointing this out. This fix would not work when the input normal is 2 channels (x, y) and z needs to be recomputed or when the input normal is not normalized. A better fix is to force the z recomputation by changing line 482 from if map_name == "normal" and num_channels == 2: to if map_name == "normal":