Process deletions

• Add a deleteFilters function to delete events by filter from the database
• Reworked the tags database table, renamed value_1 to value, dropped value_2, value_3, added a foreign key on event_id
• Enabled autovacuum on the database.
• Automatically delete events older than 7 days. Fixes #63 (closed)
• Broadcast deletions from local users to all known relays.
• Process deletion events through the pipeline, delete from our database if authorized.
• Protect against deleted events being resubmitted (not perfect).
• Improved the terminal output for migrations.
• Fix various bugs.