Delimited structs - this will allow us to skip unrecognised structs.

briar-api/src/net/sf/briar/api/serial/Reader.java

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

briar-api/src/net/sf/briar/api/serial/Writer.java

briar-core/src/net/sf/briar/messaging/AuthorFactoryImpl.java

briar-core/src/net/sf/briar/messaging/AuthorReader.java

briar-core/src/net/sf/briar/messaging/GroupFactoryImpl.java

briar-core/src/net/sf/briar/messaging/GroupReader.java

...r-core/src/net/sf/briar/messaging/MessageFactoryImpl.java

briar-core/src/net/sf/briar/messaging/MessageReader.java

briar-core/src/net/sf/briar/messaging/PacketReaderImpl.java

briar-core/src/net/sf/briar/messaging/PacketWriterImpl.java

.../src/net/sf/briar/messaging/SubscriptionUpdateReader.java

briar-core/src/net/sf/briar/serial/ReaderImpl.java

briar-core/src/net/sf/briar/serial/SerialComponentImpl.java

briar-core/src/net/sf/briar/serial/Tag.java

briar-core/src/net/sf/briar/serial/WriterImpl.java

...ests/src/net/sf/briar/messaging/PacketReaderImplTest.java

...ests/src/net/sf/briar/messaging/PacketWriterImplTest.java

briar-tests/src/net/sf/briar/serial/ReaderImplTest.java

briar-tests/src/net/sf/briar/serial/WriterImplTest.java