module to module pixel pitch variation

[krwood]

The recent changes to include module-to-module variations in 2x2 simulations seems to have an error when determining the appropriate pixel pitch. The following display is attempting to accounting for the different geometry of module 2, but there seem to be missing hits at 2 extreme edges in the yz-plane (i.e. the pixel plane) for module 2.

Modules 0,1,3 should have pixel pitches of ~4.4 mm, and Module 2 should have a pixel pitch of ~3.8 mm, as indicated in their respective multi_tile_layout geometry files. Recent commits to the develop branch of larnd-sim have aimed to implementing the functionality required to account for differences such the different pixel pitches. However, whatever the constant PIXEL_PITCH is last filled with is what will be used for calculations like determining which pixels a given track will drift towards: https://github.com/DUNE/larnd-sim/blob/develop/larndsim/pixels_from_track.py#L91

I suspect the observation above might be related to the fact that we aren't making a list of pixel pitches on a module-by-module basis for such calculations.

[krwood]

Or, @YifanC, maybe now I just understand why we have to batch module-by-module?

[krwood]

Addressed with PR #189