Add a filter to overview

On large maps especially, it can be hard to find all the resources being used and who has them since they kind of blend in with planets, and vice versa.  It would be great to have a screen that hides or "filters" out items. 

Example:  Layer system that allows you to show planets, resources, enemy units, your units.  You are zoomed out and want to see planets that could be threatened soon only, you can select exactly what units you want to show (deselecting the others).  Now you can see your planets + enemy fleets only without clutter of your fleets or resources.