Update fhicl configuration

[AndrewEdmonds11]

This PR includes major changes to the fhicl configuration structure for EventNtuple. I had Sonnet take a first pass and then I made some manual tweaks.

The highlights:

• there are now separate configuration blocks for trk, calo, and crv branches that can be individually turned on/off with e.g. trk.fill : false
• there is also a top-level global switch for turning MC off and on (EventNtuple.mc.fill : false)
• some fhicl parameters have changed names:
  • branches is now trk.fits, which is a better description
  • the subconfiguration leaf branch is now branchname (i.e. you now do trk.fits[0].branchname : "dem" if you wanted to separate the fits into separate branches)

I've also added a new and improved validation script that can be more easily extended to new fcl files. I have added:

• from_dig-OnSpill.fcl,
• from_dig-calo.fcl, and
• from_mcs-Run1B.fcl
  to the suite of fcl files that are tested. See the updated validation README.md for more information.

This will hopefully go some way to resolving #349, #371, and #373.