## Impacted versions:
 8.0 / 9.0 / 10.0
## Steps to reproduce:
* see https://github.com/odoo/odoo/issues/11841
* in a shell
  1. create an in memory record `order = self.env['purcahse.order'].new({....})`
  2. create an in memory record with a reference to the first one `order_line = self.env['purchase.order.line'].new({'order_id': order, ....})`
  3. order_line.order_id is an in memory recordset
  4. create a record for a model that inherits from mail.thread `self.env['product.product'].create({....})`
  5. At this stage order_line.order_id is an empty recordset

## Current behavior:
 In memory records are dropped when a call is done to self.invalidate_cache
## Expected behavior:
In memory records are preserved when a call is done to self.invalidate_cache


There are lot of places where the method `invalidate_cache` is called and the silent removal of the in memory records from all environments has unpredictable effects on fields modified by a computed method or an onchange or even related fields .... Moreover since all caches are invalidated each time you create / write / unlink  (https://github.com/odoo/odoo/blob/10.0/addons/mail/models/mail_followers.py#L111) an instance of a model that inherits from 'mail.thread', the performances of the server are severely penalized.

OPW703903

self.write(cr, uid, ids, {'state': 'approved', 'date_approve': fields.date.context_today(self,cr,uid,context=context)})
        return True
    def wkf_bid_received(self, cr, uid, ids, context=None):
        return self.write(cr, uid, ids, {'state':'bid', 'bid_date': fields.date.context_today(self,cr,uid,context=context)})
    def wkf_send_rfq(self, cr, uid, ids, context=None):
        '''
        This function opens a window to compose an email, with the edi purchase template message loaded by default
        '''
        if not context:
            context= {}
        ir_model_data = self.pool.get('ir.model.data')
        try:
            if context.get('send_rfq', False):
                template_id = ir_model_data.get_object_reference(cr, uid, 'purchase', 'email_template_edi_purchase')[1]
            else:
                template_id = ir_model_data.get_object_reference(cr, uid, 'purchase', 'email_template_edi_purchase_done')[1]
        except ValueError:
            template_id = False
        try: