This PR is geared towards the BNB nue:

• Added post-processors used to correct pitfalls of the shower reconstruction
• Added attributes to RecoParticle objects to store shower reconstruction quality metrics
• Added support to merge track fragments into showers
• Added basic support for logical post-processor ordering checks
• Added option to anchor start dE/dx estimation
• Added option to incorporate direction information into start dE/dx information
• Added option to draw particle start directions in the visualization tools

It also includes bug fixes:

• The clustering quality analysis script did not work when run on the fly
• The fragment truth loader had a typo and could not load depositions_g4
• The angular check in the vertex post-processor when using the update_primaries option checked cosine against an angle. Now correctly checks an angle against the angular threshold
• The transparency correction checks that a run ID is indeed provided (only way to fetch map)