Map Glyphs

Got rid of notion of 'element'.  The glyph on a map seems to be the only valid example of what we'd consider an element.

There's some weird stuff for get/set state for the ArrayProperty, let me know if you can think of a better way to load/save an array of DataSets.

And I need a little guidance for adding undo/redo. And I'm not sure if the 'unsaved changes' thing is popping up at the right times.. ><