Implicit groups

Implicit groups are groups defined automatically by PICA to ease host and group arithmetic. Currently, there are only two implicit groups defined:

all

Obviously, it refers to all of the hosts or objects (depending on where we use it).

alarms

Used in objects, it refers to all of the objects with type alarm, and all of the files uses'd by them.

Moreover, if sysdown is not defined, PICA will define it automatically (to a empty list, of course).