Add per-chat option for received markers
When the account privacy option to send received receipts is disabled, the displayed receipt is nevertheless sent. The result is that the sent message immediately gets double checkmark sign when displayed. While the option does exactly what it says (it does not mention displayed receipt), I think that this behavior can be considered buggy. From the privacy viewpoint I would expect that when received receipts are disabled, so are displayed receipts.
Alternativelly, for full control, one could add a second option specifically for displayed receipts.