Adds a score layer to track arbitrary floats per voxel

[hermannsblum]

Two options are implemented currently:

• running average of values
• overwriting by keeping the latest value

I focused on the single-tsdf case, not sure if there are more modifications necessary for the multi-tsdf?

If this looks in general good to you, the uncertainty voxel should probably be removed and rather integrated as an exponential decay option in the score layer.