[ENH] Add a default reproin heuristic

[mattcieslak]

Ideas:

1. Make it a commandline option: just have some basic pattern matching that ignores fieldmaps
2. Make it an importable function that can be included in a heuristic. Something like:

from fw_heudiconv import reproin

infotodict = reproin

IntendedFor = { ... }
MetadataExtras = { ... }

[TinasheMTapera]

@mattcieslak went over our options today. I like the importable function option as it's less overhead. In fact, if they want to use reproin in their heuristic.py, then it's simply a matter of them knowing how to import it from heudiconv. You can do it like this:

import importlib

module = importlib.import_module('heudiconv.heuristics.{}'.format(<heuristic_in_heudiconv>))
infotodict = module.infotodict

So in the CLI there's really not much to change. The next thing I'll be working on is how to add this as an option in the gear

[TinasheMTapera]

Should work now, keeping the branch separate for a little in case something comes up