[IMP] crm_leads: default filter is 'not dead' instead if 'unassigned' and displays an info message in the crm.stage form view. Dead leads should'nt be included in the default view since they can pollute the view over time. Instead, a filter for all leads (except the dead ones) is used by default. A small info message inform the user that the "dead" status is equivalent to setting probabilities to 0 and to fold the stage in kanban for a crm.stage.