-finished the addToStackPane() function with layers, and configured it so that it will always add to the correct layer and overlap correctly
-completed the moveToTopOfLayer() function as well
-debugged all features that implement layers
-commented and organized some code
-fixed a bug with the drag-drop feature that arose, which hides the feature when it is dropped
Implement Cities! Find a graphic that can replace the map element and store it somewhere in the workfolder. Then go on to finish the rest of the quiz-taking features.