report # of swarms in status, add forget method

tracker/src/main/groovy/com/muwire/tracker/SwarmManager.groovy

@@ -46,6 +46,10 @@ class SwarmManager {
         swarm.add(e.results[0].sender)            
     }
     
+    int countSwarms() {
+        swarms.size()
+    }
+    
     void track(InfoHash infoHash) {
         Swarm swarm = swarms.computeIfAbsent(infoHash, {new Swarm(it)} as Function)
         if (swarm.needsQuery()) {
@@ -61,4 +65,9 @@ class SwarmManager {
             originator : core.me, sig : sig.data, queryTime : timestamp, sig2 : DataUtil.signUUID(uuid, timestamp, core.spk)))
         }
     }
+    
+    boolean forget(InfoHash infoHash) {
+        Swarm swarm = swarms.remove(infoHash)
+        swarm != null
+    }
 }

tracker/src/main/groovy/com/muwire/tracker/TrackerService.java

@@ -3,4 +3,5 @@ package com.muwire.tracker;
 public interface TrackerService {
     public TrackerStatus status();
     public void track(String infoHash);
+    public boolean forget(String infoHash);
 }

tracker/src/main/groovy/com/muwire/tracker/TrackerServiceImpl.groovy

@@ -25,6 +25,7 @@ class TrackerServiceImpl implements TrackerService {
     
     public TrackerStatus status() {
         status.connections = core.getConnectionManager().getConnections().size()
+        status.swarms = swarmManager.countSwarms()
         status
     }
     
@@ -38,4 +39,10 @@ class TrackerServiceImpl implements TrackerService {
         InfoHash ih = new InfoHash(Base64.decode(infoHash))
         swarmManager.track(ih)
     }
+    
+    @Override
+    public boolean forget(String infoHash) {
+        InfoHash ih = new InfoHash(Base64.decode(infoHash))
+        swarmManager.forget(ih)
+    }
 }