prevent adding shift in a period of time where member benefits from a exempting leave, from member space

mostly #7524 and #7413 so that "cancellations" of shift and shift_templates work fine especially when adding/changing shift

#7325 : use suppleant_member_id instead of parent_id or is_associated_people to perform binom checks

allow bdm to configure a message that is displayed when a member selects a creneau matching (day of week, time) from member space

ajout nouveau champ configurable au process d'inscription : profession (champ également rendu modifiable post circuit d'inscription depuis l'espace membre)