Introduce new method areListenersPaused() to interface SelectionModel

* Use areListenersPaused() in BranchGraphSelectionAdapter to find out, if listeners have been paused outside of this method and only in case they are not: pause listeners, select the branch vertex and resume listeners
* Without this change a selection of many branch spots at the same time caused that resumeListeners() was called with high frequency resulting in low performance, when selecting many branch spots at the same time

src/main/java/org/mastodon/adapter/SelectionModelAdapter.java

@@ -162,4 +162,10 @@ public void pauseListeners()
 	{
 		selection.pauseListeners();
 	}
+
+	@Override
+	public boolean areListenersPaused()
+	{
+		return selection.areListenersPaused();
+	}
 }

src/main/java/org/mastodon/model/DefaultSelectionModel.java

@@ -389,4 +389,10 @@ public void pauseListeners()
 	{
 		emitEvents = false;
 	}
+
+	@Override
+	public boolean areListenersPaused()
+	{
+		return !emitEvents;
+	}
 }

src/main/java/org/mastodon/model/SelectionModel.java

@@ -166,4 +166,6 @@ public interface SelectionModel< V extends Vertex< E >, E extends Edge< V > >
 	public void resumeListeners();
 
 	public void pauseListeners();
+
+	boolean areListenersPaused();
 }

src/main/java/org/mastodon/model/branch/BranchGraphSelectionAdapter.java

@@ -75,6 +75,12 @@ public void pauseListeners()
 		selection.pauseListeners();
 	}
 
+	@Override
+	public boolean areListenersPaused()
+	{
+		return selection.areListenersPaused();
+	}
+
 	@Override
 	public boolean isSelected( final BV vertex )
 	{
@@ -123,9 +129,12 @@ public boolean isSelected( final BE edge )
 	@Override
 	public void setSelected( final BV vertex, final boolean selected )
 	{
-		selection.pauseListeners();
+		boolean areListenersPaused = selection.areListenersPaused();
+		if ( !areListenersPaused )
+			selection.pauseListeners();
 		setVertexSelected( vertex, selected );
-		selection.resumeListeners();
+		if ( !areListenersPaused )
+			selection.resumeListeners();
 	}
 
 	private boolean setVertexSelected( final BV branchVertex, final boolean selected )