Add Date Indicator for SMS Messages

[drinkyourcoffee]

I noticed that, while there are time stamps on SMS messages, there are no date stamps to help understand when messages were sent or received. Adding a date stamp to any messages that were not sent or received on the current date would be useful in many ways. To keep the look of messages clean, this could be integrated in the way that the Signal app does it: by placing a heading with the date above the messages that pertain to that date.