[Seaside] cleaning up in 2.5

[Kamil Kukura]

Avi Bryant wrote:
> Hm.  How is overriding #isActive more predictable?
> Alternatively - what if #unregisterExpiredHandlers happened at 
> predictable time intervals, like once every 10 minutes?

Yes, this makes more pleasant reason for having database connections 
stored in session. Also, besides this collectTimeout parameter, maybe it 
would be useful to have some boolean determining if all sessions should 
be unregistered on image shutdown.

-- 
Kamil