Compilation speed-up patch (only compile modify files). (Paul Stoffregen)

http://code.google.com/p/arduino/issues/detail?id=638

app/src/processing/app/Base.java

@@ -1010,6 +1010,7 @@ public class Base {
               Preferences.set("target", (String) getValue("target"));
               Preferences.set("board", (String) getValue("board"));
               onBoardOrPortChange();
+              Sketch.buildSettingChanged();
             }
           };
         action.putValue("target", target.getName());