Fixed non-attacking related movement while mobs are snared

On live a nec/shd normal splitting involved snaring the mob you want
and FDing after they moved enough. The non-snared mobs would return home
and the snared mob would just sit there until it was no longer snared.
There is even a nice flash video! http://www.dzert.com/downloads/eq/fd02.swf
This might need some tweaking, but I'm not sure of any instances where it would
break things...