[CHG] Improve the _write_name method
* trying to coerce to the correct lastname if the firstname is untouched
* resetting the firstname if contact is a company
[FIX] Avoid to replicate the firstname into the name when duplicating a partner
[FIX] Avoid to replicate the firstname into the name when duplicating a user
[CHG] Restore the required attribute of the field name in user form
[CHG] Beautify the inner form for children contacts (placing fields as in the main form)
[FIX] Allow edition of the field name in the inner form if child is a company