Treatment of MM/sTGC deformities perpendicular to the layer plane

We have found out that displacements of NSW hits in a direction perpendicular to the nominal layer plane (due to chamber deformations) have no effect in muon reconstruction. This is because the fitters consider only on-plane displacements, whereas the coordinate perpendicular to the layer is taken from the un-derformed geometry in order to estimate the track intersection.

Since we can't propagate the track to the deformed surface in order to get an accurate residual (i.e. we can't get the actual intersection), we are going to do the inverse, i.e. propagate the hit back to the nominal surface, following the direction of the track.

Tagging: @jojungge @pscholer @stavrop @iodice @rosati @amelung