Fixed a bug dropping widget on nest

Was 'dropped' twice.
Removal from backside of boxes working

Was trying to remove it from the frontside instead.
Added error handling
Index files now contain 2-holed boxes
Robots now pick up top widget on nests
Watched robots move to covered nest

When removing top widget.
Fixed CSS problem with numbers on nests in boxes

The width was 80% of the box rather than the hole.
Removed spurious warning code.
Update parent when a robot takes widget from nest
Improved watched robot pick up widget from nest

Geometry better and is always visible but location isn't perfect.