Impacted versions:
10.0 + e

Steps to reproduce:
1) Create a salary rule that has 'appears_on_payslip' = False.
- An example would be a company contribution that the employee does not need to see.
  2) Add it to a salary structure
  3) run a payroll/payslip calculation

Current behavior:
Numerous thing.
1) Every time you compute sheet, you will duplicate these 'hidden' lines
2) details_by_salary_rule_category no longer has any of the hidden lines, though they certainly contribute to categories (e.g. tests will fail, and bad things)
3) when using hr_payroll_account, lines with contribution registers and accounts that SHOULD be on the journal entry are not !!

Expected behavior:
1) every time you compute the sheet, the lines should be deleted and recalculated
2) details_by_salary_rule_category should have all categories (to be able to make complex rules and tests)
3) journal entry should have a line for every line with an account

Pull Request eminent.

"""
        @param contract_id: id of hr.contract to be tested
        @return: returns True if the given rule match the condition for the given contract. Return False otherwise.
        """
        self.ensure_one()
        if self.condition_select == 'none':
            return True
        elif self.condition_select == 'range':
            try:
                result = safe_eval(self.condition_range, localdict)
                return self.condition_range_min <= result and result <= self.condition_range_max or False
            except:
                raise UserError(_('Wrong range condition defined for salary rule %s (%s).') % (self.name, self.code))
        else:  # 
            try:
                safe_eval(self.condition_python, localdict, mode='exec', nocopy=True)
                return 'result' in localdict and localdict['result'] or False
            except:
                raise UserError(_('Wrong python condition defined for salary rule %s (%s).') % (self.name, self.code))
class HrRuleInput(models.Model):
    _name = 'hr.rule.input'
    _description = 'Salary Rule Input'
    name = fields.Char(string='Description', required=True)
    code = fields.Char(required=True, help="The code that can be used in the salary rules")
    input_id = fields.Many2one('hr.salary.rule', string='Salary Rule Input', required=True)
class HrPayslipLine(models.Model):