StatusStorage::SQLite: a bit more strict check for status objects given to put_statuses().
t/StatusStorage_SQLite: write tests about vacuum_on_delete.
StatusStrage::SQLite: implement vacuum_on_delete option and vacuum() method.
t/StatusStorage_SQLite: add tests about manipulating timestamp columns directly.
StatusStorage::SQLite: bug fix: timestamp format was weird.
t/StatusStorage::SQLite: add tests about manipulating level column directly.
t/StatusStorage::SQLite: add tests about non-UTC timestamps. Tests complete.
xt/StatusStorage_AEDelayed: fix invocation of test_storage_truncation().