cli

[geritwagner]

This PR introduces cli operations for bib-dedupe:

 # end-to-end merge
 bib-dedupe merge -i records.csv -o merged.csv --stats

 # stepwise execution
 bib-dedupe prep -i records.csv -o records.prep.csv
 bib-dedupe block -i records.prep.csv -o pairs.csv
 bib-dedupe match -i pairs.csv -o matches.csv

 # review and apply maybe cases
 bib-dedupe match -i pairs.csv -o matches.csv --export-maybe --records records.csv
 # edit the generated maybe_cases.csv, then
 bib-dedupe import-maybe -i matches.csv -o matches.reviewed.csv
 bib-dedupe merge -i records.csv -o merged.csv --import-maybe

TODO:

• Loading and saving BibTeX requires an external library (e.g., colrev).
• TODO : remove the step-by-step option and only offer the straight-through option (intermediate results would be kept in memory anyway)