Only attach the dcrd notification listener after all other startup tasks
have been completed.
Attaching the listener before this can result in the notification
handler being invoked whilst startup tasks are still running, which
isn't necessarily a problem, but it is unnecessary and makes a mess of
logging.
Periodic database backups are no longer started automatically in database.Open(), and the backup written by database.Close() can now be disabled.
Only vspd itself requires backups, they are not useful for test code or future upcoming tools such as vote-validator.
* Update linter to 1.49.0
* Move vspd into cmd directory.
This is standard practise in Decred golang repos. Especially useful when multiple executables are built from a single repo.
* Ignore bins in new dir.
