Add timestamps to chat

[vinszent]

Shouldn't be enabled by default but have a setting where it can be turned on and off.

[vinszent]

@CyberStar1

Here is a possible solution:

1. Add a timestamp field to GtIrcMessage and set it when creating a message in gt-irc.c.
   • It could be either a Unix timestamp or GDateTime I guess depending on performance and ease of use.
2. Display timestamp in the same way Twitch does it in their chat. This will be located gt-chat.c just look at how badges, usernames, messages are inserted for a gist of how it works.
3. Add a setting to turn it on.