Use the transport's idle timeout, not a hardcoded value.

briar-api/src/org/briarproject/api/plugins/Plugin.java

@@ -17,6 +17,9 @@ public interface Plugin {
 	/** Returns the transport's maximum latency in milliseconds. */
 	long getMaxLatency();
 
+	/** Returns the transport's maximum idle time in milliseconds. */
+	long getMaxIdleTime();
+
 	/** Starts the plugin and returns true if it started successfully. */
 	boolean start() throws IOException;
 

briar-api/src/org/briarproject/api/plugins/TransportConnectionWriter.java

@@ -15,6 +15,9 @@ public interface TransportConnectionWriter {
 	/** Returns the maximum latency of the transport in milliseconds. */
 	long getMaxLatency();
 
+	/** Returns the maximum idle time of the transport in milliseconds. */
+	long getMaxIdleTime();
+
 	/** Returns the capacity of the transport connection in bytes. */
 	long getCapacity();
 

briar-api/src/org/briarproject/api/plugins/duplex/DuplexPlugin.java

@@ -7,9 +7,6 @@ import org.briarproject.api.plugins.Plugin;
 /** An interface for transport plugins that support duplex communication. */
 public interface DuplexPlugin extends Plugin {
 
-	/** Returns the transport's maximum idle time in milliseconds. */
-	long getMaxIdleTime();
-
 	/**
 	 * Attempts to create and return a connection to the given contact using
 	 * the current transport and configuration properties. Returns null if a