[MERGE] Mail: improve incoming/outgoing emails behavior

Main:
- updated overall code to match the new mail openerp tools
- message_route: after checking the headers to find if the incoming email is a reply in an existing discussion, it checks whether the email is a reply to a private discussion (without model, res_id), based on the message_id of the mail; it then relies on the aliases then fetchmail, as before
- incoming emails and quick posting through Chatter now calls message_post_user_api (based on old message_post_api), that performs some things the composer do on its side (adding recipients of a replied message, cleaning the content)
Misc:
- general: updated modules according to the new tools mail functions
- general: message related to a new app installation now have a comment subtype, meaning they will effectively be pushed
- mail: improved set_message_read, fixed a bug with message_id
- fetchmail: fixed a bug in fetchmail module about non-existing variable
- portal: updated demo data

bzr revid: tde@openerp.com-20121114150500-pzj8zhyt5e29aekb