Fix charts for SQLite

This fixes a regression introduces in 6bc0162; that changed so that stat
rows were no longer stored if there are no visits to store. That works
fine, except for hit_stats in SQLite since it will do a "select",
"delete", merges with new pageviews, and then an insert. But if there
are no new visits (only pageviews) it will never re-insert the rows.

So check the full array instead, and write a migration to correct the
wrong data.

Prepare v2.4.0 release

2.3.0 release

Return default views if database is invalid

This affects very few people, and better a quick fix for now.

Include .gotxt migrations in binary

Fixes arp242#569

drop-role migration should be PostgreSQL-only

Fixes arp242#569

Do'h; do it correct

Add missing migration to schema

Otherwise creating a new database would fail in PostgreSQL (or
specifically, running migrations for it).

Fixes arp242#550

Update gogo-release file

Fix migration yet again

De-duplicate both the "short" and "normal" versions.