Various admin interface improvements
Various admin interface improvements

- Launch game in popup sized to game size
- Show bigger room thumbnails in sidebar
- Remove Exits/Assets tabs
- Move Exits block to image template
- Various minor class changes
- Various minor text changes
- Adding background-image field to text rooms
- Adding thumbnail field to text rooms
- Removing client block (previously commented out, but we really don't need it)

bentobx/iV,bentobx/iV