ddrsql command

[gjost]

• load collection data into sqlite database
• lastmod time for object
• compare last git commit timestamp to lastmod
• hook up to datasette
• script for iterating through all collections in repository

[gjost]

DONE so far

• ddrsql load command that loads an entire collection's metadata into SQLite
• ddrsql load handles UPDATEs as well as INSERTs
• ddrsql find command that finds all the collection repositories in a directory and indicates whether the SQL database or the JSON files are more up-to-date