[client] Fix new day printing

[marcopeereboom]

No description provided.

[jrick]

Leaving this running overnight to see if it fixes the issue, but upon starting a new client instance, I already see day changed messages in-between two different messages on the same day. For example:

10:38:03 group conversation started: foo
10:38:03 <jrick> bar
10:38:19 first message received on 2 January 2019
10:38:19 <marco> baz

This is how the client has always operated, but it still seems like a bug to me. I would expect it to display:

10:38:03 group conversation started: foo
10:38:19 first message received on 2 January 2019 <- this is server time, not client time, and not sure what timestamp is actually best here
10:38:03 <jrick> bar
10:38:19 <marco> baz

or to just leave out the first day changed message entirely.