'Start the process \'Merge with Manual Check\'. Fill the wizard according to the group_by and exclude
options, and redirect to the first step (treatment of first wizard line). After, for each subset of
partner to merge, the wizard will be actualized.
- Compute the selected groups (with duplication)
- If the user has selected the \'exclude_xxx\' fields, avoid the partners'

@api.multi
def action_start_manual_process(self):

    self.ensure_one()
    groups = self._compute_selected_groupby()
    query = self._generate_query(groups, self.maximum_group)
    self._process_query(query)
    return self._action_next_screen()
