WIP: erp5_messenger: initial commit
New bt for erp5 messenger tool
- gadgetField for Messenger Thread view: it shows dinamically the list of posts for the current thread, and allows to add new posts. Bug fixing pending.
- no editor yet: we have to decide if it will be in a new form view in Thread or within the gadgetField
- scripts to add and get the post temporarily refers to post module until a new module and data structure is defined for the posts.
- check bt dependencies