Filter objects based on their position in the kill chain

Add the ability to filter objects to display based on their position in the kill-chain…  For example, I may want to hide “Reconnaissance”-related objects from my view to reduce clutter or only display “Command and Control” and “Actions on Objectives” to zero in on the most critical elements.

One complication is that we support multiple “kill-chain” models (not just the LMCO one).  
