Updates DecalRoad, MeshRoad and River to be able to write out via persistManager using specialityField functions, similar to ConvexShape

Fixes behavior with gamemode selection in ChooseLevelMenu so if there is only one gamemode, it is auto-selected and advances to the level selection
Update ExampleLevel in ExampleModule to have updated gamemodes field name

Engine/source/environment/decalRoad.cpp

@@ -322,7 +322,7 @@ void DecalRoad::initPersistFields()
    addGroup( "Internal" );
 
       addProtectedField( "node", TypeString, 0, &addNodeFromField, &emptyStringProtectedGetFn,
-         "Do not modify, for internal use." );
+         "Do not modify, for internal use.", AbstractClassRep::FIELD_HideInInspectors | AbstractClassRep::FIELD_SpecialtyArrayField);
 
    endGroup( "Internal" );
 
@@ -473,6 +473,36 @@ bool DecalRoad::writeField( StringTableEntry fieldname, const char *value )
    return Parent::writeField( fieldname, value );
 }
 
+U32 DecalRoad::getSpecialFieldSize(StringTableEntry fieldName)
+{
+   if (fieldName == StringTable->insert("node"))
+   {
+      return mNodes.size();
+   }
+
+   return 0;
+}
+
+const char* DecalRoad::getSpecialFieldOut(StringTableEntry fieldName, const U32& index)
+{
+   if (fieldName == StringTable->insert("node"))
+   {
+      if (index >= mNodes.size())
+         return NULL;
+
+      const RoadNode& node = mNodes[index];
+
+      char buffer[1024];
+      dMemset(buffer, 0, 1024);
+      dSprintf(buffer, 1024, "%f %f %f %f", node.point.x, node.point.y, node.point.z, node.width);
+
+      return StringTable->insert(buffer);
+   }
+
+   return NULL;
+}
+
+
 void DecalRoad::onEditorEnable()
 {
 }