First update for truth derivations
My last attempt was a bit too much at once, so I'm breaking this up a bit more. This brings three truth tools up from release 21.2 to master: a tool for decorating GenFilter outcomes, a tool for decotating truth-level event density, and a tool for writing truth metadata. There's a small tweak to the python to not ignore the gen filter tool, now that it exists. More can come later, but this is a start.
Does a chunk of !37659 (closed)
Note that after this, PHYS is still working, and TRUTH derivations are still not.