group watchers

[Jochen Stenzel]

Hello,

two slight suggestions for group watchers. Accidentally I wrote:

$groupWatcher->add(\$i);

where $i was still unused (of course, in a hack without "use strict"). This causes a 
segmentation fault.

Being on this way, I tried:

$groupWatcher->add(\$groupWatcher);

which produced the message:

"Attempt to use destroyed object (RV=0x81634dc (null)=0x80f1b8c) at ..."

                        Jochen