Issue COMPILER-DIAGNOSTICS, v7

[Kent M Pitman <KMP@STONY-BROOK.SCRC.Symbolics.COM>]

btw, i've been thinking more about the lispm's NOTIFY and i'm starting to
feel uncomfortable about using it as a model, and hence about using the
names NOTIFY and NOTIFICATION. at this point, i think whether i'd go along
with those particular names depends on what kind of info it is going to
type out.

The kinds of things people call NOTIFY for on lispm are things like:
 GC status: GC needed, GC happening, almost out of room, etc.
 Remote file server is going down (or has just come up).
 Power in machine room going down.
 Some activity (a.k.a. window, process, job, or fork) wants intervention.
 Message from another user has arrived.
Note that these are all things which tend not to be associated with the
ongoing activity (compilation, editing, ...) which the user is in at the time
the message is received.

Note also that on the LispM the notification is not dealt with by signalling.
Instead, it is an asynchronous message to the activity. The activity then
decides whether to write on its own window, pop up another window, defer
the notification until later, or whatever.