Added BookmarksWindow class.

-BookmarksWindow: Added a TreeView that displays all the active
bookmarks. Added functionality of right-clicking an item in the TreeView
so that the map centers on it.
-CommandWindow:  Added title and description to the JSObject. Made sure
adding and removing a marker updates the list of the BookmarksWindow and
keeps the TreeView up to date.
-MapUtils: Removed unused import.
-MapWindow: Added a BookmarksWindow so that every map has it's own
window.
-NCCMain: Made some changes I rollbacked later, added some comments.