Add prepared flag to schematics and refactor related logic

SchematicSystem/SchematicSystem_Core/src/de/steamwar/schematicsystem/commands/schematiccommand/SchematicCommandUtils.java

@@ -428,6 +428,8 @@ public class SchematicCommandUtils {
             return;
         }
 
+        node.setPrepared(false);
+
         if (type.writeable()) {
             node.setSchemtype(type);
             SchematicSystem.MESSAGE.send("UTIL_TYPE_DONE", player);