GEM- GUI Editor for MapCss V.5

I rebuilt GEM to be a more reflexive and adaptable UI, and added several feature requested by various JOSM editors, such as the ability to edit multiple users at once.

The "Isolate User" function is now "HIDE/SHOW" User and works much better.

Close handler exports file without time search, toggle UID or hidden users so that original file isn't overwritten permanently with search specific data.

Table widget replaced with QTreeWidget which is much easier to work with and allows additional functionality