[crossfire] Code restructuring

[Nicolas Weeger (Laposte)]

Hello, here are my 2 cents of €.

I'll agree to some points made here and there :)

Such a restructuration is a good idea, and will hopefully enable to clean some 
code. It should take advantage of unit tests currently being added.

IMO this should be done in current HEAD branch, having a "stable" branch per 
Yann's suggestion - after all HEAD is supposed to be unstable ^_-

Yes it'll be a non-trivial task, but worth it, for a 2.0 release (which is 
after all a big symbolic number!).

I'd say to put the callback in the archetype itself. But I'd enable a plugin 
to override such callbacks, to change some behaviours.

Nicolas