Modified timesamps

Modified the previous commit after discussing it with Soliton. We agreed
on sending timestamps to other players and using them [received timestamps]
in displaying, with a fallback to using local time if received message
without timestamp.

This fixes several issues:
1) when viewing replays the time would be the one of the actual game
insted of the time of viewing the replay;
2) previously, when opening some dialog while players send messages and
then closing it — chat messages would have timestamp of when the dialog
windows was closed, not the time when messages were sent.

This also introduces one new issue:
1) if a player has time set up wrong, the time stamp will be incorrect.
For example, when instead of setting to the right timezone player just
adjusted system time by adding or subtracting hours with incorrect
timezone selected.
Cleaning

Removed new line.
Refactoring

Renamed undescored variable so it won't get taken for class variable by
mistake.