Methods common to all nobservers
================================

The nobserver base type is one of two base types (the other being observer)
for objects whose primary purpose to derive outputs from layers (directly or
via other observers) outside of the "natural" computation of that object. 
`nobserver` is triggered by modification events used for logging, whereas
`observer` must be polled.

description
-----------

	some_nobs description

The description of `some_nobs` will include the `Enabled` bit (disabled
indicating that events on observed objects should be ignored); and
`Triggers` a list of observed objects whose modification will cause 
further processing.

add_trigger
-----------

	some_nobs add_trigger stalkee...

Adds one or more objects listed as `stalkee` to the trigger list.

rem_trigger
-----------

	some_nobs rem_trigger stalkee...

Removes one or more objects listed as `stalkee` to the trigger list.

disable
-------

	some_nobs disable

Start temporarily ignoring trigger modification events.

enable
-------

	some_nobs enable

Stop temporarily ignoring trigger modification events.