[WIP] fix(postproc): separate variables for traps, mothers, daughters

WHY IS THIS CHANGE NEEDED?:
- IndexError raised when processor is invoked

HOW DOES THE CHANGE SOLVE THE PROBLEM?:
- multii variable (line 208) assumes that daughters is a 2d numpy array
  with at least 2 columns.  this is wrong, both mothers & daughters are
  lists.
- bug uncovers poor handling of variables that store info on traps,
  mothers, and daughters, so refactored them too.  specifically, the
  mothers variables stored traps AND mothers information -- now i've
  separated them.
- this also means that numpy.append makes no sense and i use
  numpy.column_stack() instead.

WHAT SIDE EFFECTS DOES THIS CHANGE HAVE?:
- tech debt: potentially more refactoring along the line in this file --
  the logic is quite convoluted.

EVIDENCE THAT COMMIT WORKS:
- yet to see

REFERENCES:
- issue #37