Allow to perform maintenance operations on workcenters. Block workorders during maintenance slots. Workcenters now gather maintenance data. Workorders gantt views adapted to show blocked slots and summed times. Change recurrence scheme, move settings from equipment/workcenter to maintenance request. This allows multiple maintenances on same element (monthly, yearly, ...) and removes the need of ir.cron See odoo#94866 See odoo/enterprise#28964 closes odoo/odoo#94866 Task: 2444754 Related: odoo/upgrade#4571 Signed-off-by: Steve Van Essche <svs@odoo.com>