Added getMaxLatency() method to transport plugins.

briar-api/src/net/sf/briar/api/plugins/Plugin.java

@@ -14,6 +14,9 @@ public interface Plugin {
 	/** Returns a label for looking up the plugin's translated name. */
 	String getName();
 
+	/** Returns the transport's maximum latency in milliseconds. */
+	long getMaxLatency();
+
 	/** Starts the plugin and returns true if it started successfully. */
 	boolean start() throws IOException;