Add a simplified logOnce method.

NCPCore/src/main/java/fr/neatmonster/nocheatplus/logging/StaticLog.java

@@ -110,6 +110,19 @@ public class StaticLog {
         }
     }
 
+    /**
+     * Convenience method to use the set log stream (see:
+     * {@link #logOnce(StreamID, Level, String, String)}).
+     * 
+     * @param level
+     * @param header
+     * @param longMessage
+     */
+    public static void logOnce(final Level level, 
+            final String header, final String longMessage) {
+        logOnce(streamID, level, header, longMessage);
+    }
+
     /**
      * Not really once: Always log the header with an id: create a hash of to be
      * logged parts and keep the hash in memory, log it with the header - only