Improve message list count implementation

git-svn-id: http://svn.code.sf.net/p/davmail/code/trunk@2095 3d1905a2-6b24-0410-a738-b14d5a86fcbd

src/java/davmail/exchange/ExchangeSession.java

@@ -1665,7 +1665,11 @@ public abstract class ExchangeSession {
          * @return message count
          */
         public int count() {
-            return messages.size();
+            if (messages == null) {
+                return count;
+            } else {
+                return messages.size();
+            }
         }
 
         /**