[🔊] Soundwave database

[perezju]

There are a few issues with the soundwave database as currently implemented:

• The constructor can be used as a context-manager (good) and this controls the lifetime of a transaction (not too bad), but does not actually close the database when done (bad). Instead the constructor should just open/close the database; and
• A separate method should be provided to context-manage the lifetime of a transaction. This allows for example to have several transactions with the same db object; not allowed by the current design.
• We should also document all of it's methods.