OpenMRP code refactoring

OpenMRP code need to be refactored, because lots of code is copied and not reused. This makes the code bloated and hard to manage. This will also reduce complexity and make room for future improvement.

For example [mrp_master_extension/mrp_bom.py]:
-------------------- CUT --------------------
if not operation.final_products_ids:
    final_product_id = final_product_obj.create(cr, uid, {
        'mrp_bom_operations_product_id': operation.id,
        'bom_id': operation.bom_id.id,
        'product_id': my_product,
        'product_qty': qty,
        'product_uom': product.uom_id.id,
        'location_id': location_ids[0]
    })
    final_product_obj.write(cr, uid, [final_product_id], {'location_id': location_ids[0]})
else:
    found = 0
    for final_product in operation.final_products_ids:
        if final_product.product_id.id == my_product:
            found = 1
            final_product_obj.write(cr, uid, [final_product.id], {'product_qty': qty})
    if found == 0:
        if not location_ids:
            raise osv.except_osv(_('Error'), _('No scrap location found.'))
        final_product_id = final_product_obj.create(cr, uid, {
            'mrp_bom_operations_product_id': operation.id,
            'bom_id': operation.bom_id.id,
            'product_id': my_product,
            'product_qty': qty,
            'product_uom': product.uom_id.id,
            'location_id': location_ids[0]
        })
        final_product_obj.write(cr, uid, [final_product_id], {'location_id': location_ids[0]})
-------------------- CUT --------------------

Could be rewritten into:

-------------------- CUT --------------------
final_product_id = final_product_obj.create(cr, uid, {
    'mrp_bom_operations_product_id': operation.id,
    'bom_id': operation.bom_id.id,
    'product_id': my_product,
    'product_qty': qty,
    'product_uom': product.uom_id.id,
    'location_id': location_ids[0]
})

found = 0
if operation.final_products_ids:
    for final_product in operation.final_products_ids:
        if final_product.product_id.id == my_product:
            found = 1
            final_product_obj.write(cr, uid, [final_product.id], {'product_qty': qty})

if found == 0:
    final_product_obj.write(cr, uid, [final_product_id], {'location_id': location_ids[0]})
-------------------- CUT --------------------