Validate the decrypted IV before creating a reader/writer.

api/net/sf/briar/api/transport/BatchConnectionFactory.java

api/net/sf/briar/api/transport/ConnectionReaderFactory.java

api/net/sf/briar/api/transport/ConnectionWriterFactory.java

...nents/net/sf/briar/transport/ConnectionDecrypterImpl.java

...ents/net/sf/briar/transport/ConnectionDispatcherImpl.java

...s/net/sf/briar/transport/ConnectionReaderFactoryImpl.java

...s/net/sf/briar/transport/ConnectionWriterFactoryImpl.java

components/net/sf/briar/transport/IvEncoder.java

.../sf/briar/transport/batch/BatchConnectionFactoryImpl.java

...net/sf/briar/transport/batch/IncomingBatchConnection.java

...net/sf/briar/transport/batch/OutgoingBatchConnection.java

...t/sf/briar/transport/stream/IncomingStreamConnection.java

...t/sf/briar/transport/stream/OutgoingStreamConnection.java

test/net/sf/briar/ProtocolIntegrationTest.java

test/net/sf/briar/transport/ConnectionDecrypterImplTest.java

test/net/sf/briar/transport/ConnectionWriterTest.java

test/net/sf/briar/transport/FrameReadWriteTest.java

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