- added invitation by <message> mechanism
- added a personal list in PEP which keep events created by user, or in which she has been invited
- new bridge methods: eventsList, and eventInviteByEmail. eventInvite is now used to invite a entity by jid (not email like before)
- on invite, an invitation message is send to invitee's jid
- when an invitation message is received, event is automatically linked in personal list
- when creating a new event, event is automatically linked in personal list