Add list_objects to temporal support, add list_accounts to account-change, list_sims to sim-change, add test
Remove warning if the latest temporal row to edit or remove has no starting date (for example, period '(,)').
Invoice generation: use 'period' to decide whether an account is active instead of the 'state' field; also, only return accounts that are active on a given date (or today), not all accounts that were once active.
Remove 'state' column from accounts. Bumps database schema to version 4.