[Pharo-project] New version of chapters

[Stéphane Ducasse]

Hi guys

I updated 
        - the exception chapter to show the interaction between 
ensure:/ifCurtailed: and exception.
        - improved a bit the chapter on block
        - improved a bit the metacello chapter with some tricks to do recursive 
walk trhout

Noury and other worked on Sockets
Andre and other worked on a new version of SmallLint.

Stef