DC2 Catch-up Tag

Too long since the tag release tag of this repo. Tagging to capture all of the activity on the scripts and documentation during 2020, including

New scripts:

• merge_truth_per_tract.py
• repartition_into_tracts.py

Updates to

• merge_forced_source_cat.py
• merge_source_cat.py
• write_gcr_to_parquet.py

DC2-Run2.2i-v0.4.0

Preparing for DC2 Run2.2i production.

DC2-Run1.2p-v0.2.0

Run1.2p phosim image generation release.

DC2-Run1.1p-v0.2.0

Run 1.1p (phosim) image generation.

v0.1.0

Initial release of phosim instance catalog generation scripts (for protoDC2).