Parse gemc evio config bank

[baltzell]

• e.g. for torus/solenoid scales, replacing command line options for evio2hipo
• evio bank tag 6
• example bank contents below (json)

"fields": {
    "ACTIVEFIELDS": [
      [
        "TorusSymmetric",
        "clas12-newSolenoid"
      ]
    ],
    "FIELDS_FILENAMES": [
      {
        "filename": "TorusSymmetric",
        "label": "torus"
      },
      {
        "filename": "clas12-newSolenoid",
        "label": "solenoid"
      }
    ],
    "SCALE_FIELD": [
      {
        "filename": "TorusSymmetric",
        "scale": -1.0
      },
      {
        "filename": "clas12-newSolenoid",
        "scale": -1.0
      }
    ]
  },

(Note, this may be replaced by gemc outputting hipo.)

[baltzell]

gemc 5.0 will be outputting HIPO soon.