should be able to pause/mute alerts with criteria

A good use case example is system monitoring on a server that's undergoing scheduled maintenance. I want the deadman alerts to keep firing for other servers, but not for the one I'm rebooting right now.

Obviously this needs to be doable without a restart, and ideally without pausing the entire TICKscript. Other hosts should continue to fire deadman alerts while `host=host-a-1` is paused.

Start from the scheduled-maintenance scenario in the issue and clarify how alert criteria should identify a paused host without restarting or pausing the entire TICKscript. Done means alerts remain active for other hosts while alerts matching host=host-a-1 can be paused and resumed at runtime.

Written by the indexing model from the issue text.