Store each connection window slot as a database row.

This is less memory-efficient but necessary for the coming forward
secrecy changes.

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

@@ -48,4 +48,7 @@ public interface ProtocolConstants {
 
 	/** The length of a message's random salt in bytes. */
 	static final int SALT_LENGTH = 8;
+
+	/** The size of the connection reordering window. */
+	static final int CONNECTION_WINDOW_SIZE = 32;
 }

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

@@ -4,13 +4,9 @@ import java.util.Collection;
 
 public interface ConnectionWindow {
 
-	long getCentre();
-
-	int getBitmap();
-
 	boolean isSeen(long connection);
 
 	void setSeen(long connection);
 
-	Collection<Long> getUnseenConnectionNumbers();
+	Collection<Long> getUnseen();
 }

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

@@ -1,6 +1,10 @@
 package net.sf.briar.api.transport;
 
+import java.util.Collection;
+
 public interface ConnectionWindowFactory {
 
-	ConnectionWindow createConnectionWindow(long centre, int bitmap);
+	ConnectionWindow createConnectionWindow();
+
+	ConnectionWindow createConnectionWindow(Collection<Long> unseen);
 }

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

@@ -5,7 +5,7 @@ import net.sf.briar.api.protocol.TransportIndex;
 
 public interface StreamConnectionFactory {
 
-	void createIncomingConnection(TransportIndex i, ContactId c, 
+	void createIncomingConnection(TransportIndex i, ContactId c,
 			StreamTransportConnection s, byte[] encryptedIv);
 
 	void createOutgoingConnection(TransportIndex i, ContactId c,