Add script to propagate entity labels from one set of .ann files to another

[wkiri]

Example use case: Because targets from different missions can appear in the same document, we have some pre-existing labels for MER and MSL targets already completed in the MPF and PHX collections. To avoid re-doing this work, we should copy over these already reviewed target names from the MPF/PHX .ann files to the new MER and MSL collections prior to human review.

Collection	MER targets	MSL targets
MPF	64	87
PHX	4	127

Sources

• MPF: /var/www/brat/data/mpf/all-reviewed+properties-v2/
• PHX: /var/www/brat/data/phx/all-reviewed+properties-v2/

The script would need to change e.g. Target-MER to Target when copying the entity annotation to the MER collection.

Envisioned solution:

$ propagate_entity_annotations.py <source_dir> <dest_dir> <source_entity_type> <dest_entity_type>

[wkiri]

This would be nice to have, but given time constraints we will skip it for now.