kinfu: Add --start-at-side flag
kinfu: Make recording path local
fixup! kinfu: Add --start-at-side flag
fixup! kinfu: Add --start-at-side flag
kinfu: Interpolate colors in marching cubes mesh extraction

Before, each triangle had a single color (all 3 vertices of the
triangle had the same color).

Now each vertex has its color correctly interpolated from the
color voxel volume.
kinfu: Fix documentation copy-pastes
Hard-code RGB focal lengths for my Xtion Pro camera
Use more custom keys
Disable reading shadow value etc. for oni replay