Read and write offers. Mostly boilerplate.

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

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

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

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

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

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

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

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

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

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

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

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