Time descriptions (yesterday, 2 days ago, ...) are not calculated correctly

Gajim git master 85bc3896

Messages Gajim shows from history (right after start or when opening a chat tab) are prepended with (configurable) timestamp and predefined date. The latter matches only till 00:00:00, then it becomes invalid.

2 days ago‎ [15:01:32] ...
...
Yesterday‎ [23:24:44] ...
‎‎Yesterday‎ [00:05:13] ...