working on better visualization

- allow passing null to Dumper.read()

dumpAst/src/main/jastadd/DumpAst.relast

 DumpAst ::= DumpNode* <PackageName> BuildConfig PrintConfig ;
-rel DumpAst.RootNode -> DumpNode ;
+rel DumpAst.RootNode? -> DumpNode ;
 
 DumpNode ::=  DumpChildNode* DumpToken* DumpRelation*
  <Name> <Label> <BackgroundColor> <TextColor> <Object:Object> <Invisible:boolean> <Computed:boolean> <ManualStereotypes>

dumpAst/src/main/jastadd/GenerationBackend.jadd

@@ -15,7 +15,7 @@ aspect GenerationBackend {
       }
 
       public TransformationOptions asRoot() {
-        return fromSource(Source.ROOT, false);
+        return fromSource(Source.ROOT, false).allowNullObjectsOnce();
       }
 
       public TransformationOptions asNormal(boolean shouldBeInvisible) {

dumpAst/src/main/jastadd/GenerationFrontend.jadd

@@ -379,7 +379,17 @@ public class DumpBuilder {
     protected DumpAst build() {
       if (result == null) {
         result = new DumpAst();
-        result.setPackageName(this.packageName == null ? this.target.getClass().getPackage().getName() : this.packageName);
+        final String packageNameToUse;
+        if (this.packageName != null) {
+          packageNameToUse = this.packageName;
+        } else {
+          if (this.target == null) {
+            packageNameToUse = null;
+          } else {
+            packageNameToUse = this.target.getClass().getPackage().getName();
+          }
+        }
+        result.setPackageName(packageNameToUse);
         result.setBuildConfig(this.buildConfig);
         result.setPrintConfig(this.printConfig);
         try {