* state (base_conf): Update. Decorates the return object with class
`state'. New class `state'.
(get_metfrag_targets, metfrag_on_state): New functions.
(write_metfrag_config): Update. Add checks for ion_mz and adduct not
being more, or less than one. Also, make filenames nicer and fix the
spectral separator.

(metfrag_run_many, metfrag_run_many_w_futures): New functions to run
metfrag.

tests: New tests and snapshots.