Use numeric IDs rather than names to identify transports.

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

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

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

...et/sf/briar/api/transport/batch/BatchTransportPlugin.java

.../sf/briar/api/transport/stream/StreamTransportPlugin.java

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

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

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

components/net/sf/briar/invitation/InvitationWorker.java

components/net/sf/briar/protocol/TransportFactory.java

components/net/sf/briar/protocol/TransportFactoryImpl.java

components/net/sf/briar/protocol/TransportReader.java

components/net/sf/briar/protocol/TransportUpdateImpl.java

...ts/net/sf/briar/protocol/writers/TransportWriterImpl.java

test/net/sf/briar/ProtocolIntegrationTest.java

test/net/sf/briar/db/DatabaseComponentTest.java

test/net/sf/briar/db/H2DatabaseTest.java

test/net/sf/briar/protocol/ProtocolReadWriteTest.java

test/net/sf/briar/protocol/writers/ConstantsTest.java

...f/briar/transport/batch/BatchConnectionReadWriteTest.java