Launcher.java: falls back on ZmtGuiState if there is no GUI class

build.gradle: changed zmt-core dependency to 0.21

build.gradle

@@ -24,7 +24,7 @@ description = "Library for launching ZMT simulations"
 
 dependencies {
     compile group: 'args4j', name: 'args4j', version: '2.+'
-    compile 'de.zmt:zmt-core:0.17.+'
+    compile 'de.zmt:zmt-core:0.21.+'
     
     // configuration needed when converted to project dependency
     testCompile group: 'de.zmt', name: 'zmt-core', version: '0.+', classifier: 'test', configuration: 'test'

src/main/java/de/zmt/launcher/Launcher.java

@@ -255,11 +255,11 @@ public class Launcher {
         protected void process(LauncherArgs args, ZmtSimState simState, Iterator<Path> pathIterator) {
             simState.setOutputPath(pathIterator.next());
 
-            Class<? extends ZmtGUIState> guiStateClass;
+            Class<? extends ZmtGUIState> guiStateClass = ZmtGUIState.class;
             try {
                 guiStateClass = context.classLocator.findGuiStateClass(args.getSimName());
             } catch (ClassNotFoundException e) {
-                throw new ProcessFailedException(e);
+                logger.log(Level.INFO, "GUI state class not found: " + e.getMessage() + ". Using default.");
             }
 
             final ZmtGUIState guiState = createGuiState(guiStateClass, simState);