Style: Combine file extension filters

CityDoctorParent/Extensions/CityDoctorGUI/src/main/java/de/hft/stuttgart/citydoctor2/gui/OpenFileDialog.java

@@ -120,8 +120,7 @@ public class OpenFileDialog {
 			if (fc == null) {
 				fc = new FileChooser();
 				fc.setTitle(Localization.getText("OpenFileDialog.select"));
-				fc.getExtensionFilters().add(new ExtensionFilter("GML/XML", "*.gml", "*.xml"));
-				fc.getExtensionFilters().add(new ExtensionFilter("ZIP", "*.zip"));
+				fc.getExtensionFilters().add(new ExtensionFilter("GML/XML/ZIP", "*.gml", "*.xml", "*.zip"));
 				fc.getExtensionFilters().add(new ExtensionFilter(Localization.getText("MainWindow.all"), "*.*"));
 			}
 			File dir = new File(Settings.get(Settings.LAST_OPEN_FOLDER, ""));