AnnotationModel uses inefficient iteration over map (Fixes #21)

AnnotationModel.cleanup(boolean, boolean) iterates over map with keyset
iterator and does lookup for every value from iterator. With ~10_000
annotations this is not fun anymore. Similar code in other places. That
can be improved by using entryset iterator.

See https://github.com/eclipse-platform/eclipse.platform.text/issues/21

org.eclipse.text/src/org/eclipse/jface/text/source/AnnotationModel.java

@@ -640,13 +640,13 @@ private void cleanup(boolean fireModelChanged, boolean forkNotification) {
 			fDocumentChanged= false;
 
 			ArrayList<Annotation> deleted= new ArrayList<>();
-			Iterator<Annotation> e= getAnnotationMap().keySetIterator();
 			IAnnotationMap annotations= getAnnotationMap();
-			while (e.hasNext()) {
-				Annotation a= e.next();
-				Position p= annotations.get(a);
+			Iterator<Entry<Annotation, Position>> iterator = annotations.entrySet().iterator();
+			while (iterator.hasNext()) {
+				Entry<Annotation, Position> entry= iterator.next();
+				Position p= entry.getValue();
 				if (p == null || p.isDeleted())
-					deleted.add(a);
+					deleted.add(entry.getKey());
 			}
 
 			if (fireModelChanged && forkNotification) {
@@ -789,10 +789,11 @@ public void removeAllAnnotations() {
 	protected void removeAllAnnotations(boolean fireModelChanged) {
 		IAnnotationMap annotations= getAnnotationMap();
 		if (fDocument != null) {
-			Iterator<Annotation> e= getAnnotationMap().keySetIterator();
+			Iterator<Entry<Annotation, Position>> e= getAnnotationMap().entrySet().iterator();
 			while (e.hasNext()) {
-				Annotation a= e.next();
-				Position p= annotations.get(a);
+				Entry<Annotation, Position> entry= e.next();
+				Annotation a= entry.getKey();
+				Position p= entry.getValue();
 				removePosition(fDocument, p);
 //				p.delete();
 				synchronized (getLockObject()) {