Add !seen command that tells the last time a user did something

[ghost]

I was going to say add a "-l" flag like denice and neuro had but everyone always used it all the time, so the default output might as well be similar to that and include the user's last message/action.

Also please use relative time for output...maybe add a flag you can use to get absolute time but I don't think anyone is ever going to use it because it's much easier to figure out what the date was 1 day and 3 hours ago was than to figure out how many hours it's been since October 24 12:10.