Decouple the database from IO.

api/net/sf/briar/api/db/DatabaseComponent.java

api/net/sf/briar/api/protocol/Batch.java

api/net/sf/briar/api/protocol/Message.java

api/net/sf/briar/api/protocol/PacketFactory.java

api/net/sf/briar/api/protocol/ProtocolWriter.java

api/net/sf/briar/api/protocol/ProtocolWriterFactory.java

api/net/sf/briar/api/protocol/RawBatch.java

api/net/sf/briar/api/protocol/Request.java

api/net/sf/briar/api/protocol/Types.java

api/net/sf/briar/api/protocol/writers/AckWriter.java

api/net/sf/briar/api/protocol/writers/BatchWriter.java

api/net/sf/briar/api/protocol/writers/OfferWriter.java

.../sf/briar/api/protocol/writers/ProtocolWriterFactory.java

api/net/sf/briar/api/protocol/writers/RequestWriter.java

.../briar/api/protocol/writers/SubscriptionUpdateWriter.java

.../sf/briar/api/protocol/writers/TransportUpdateWriter.java

api/net/sf/briar/api/serial/SerialComponent.java

components/net/sf/briar/db/Database.java

components/net/sf/briar/db/DatabaseComponentImpl.java

components/net/sf/briar/db/DatabaseModule.java