[IMP] Optimize chatter: remove insert_message method, instead of push each message to DOM using insert_message, create render_thread that will render each of it's message

[FIX] :  show more buttons not appear

[IMP] : code to optimize loading time
Merge branch 'master-optimize-chatter-rga' of https://github.com/odoo-dev/odoo into master-optimize-chatter-rga
[FIX] : message are not display in proper order