Make coalition scoreboard available after event ends

ih8regin

Currently, the only way to track coalition activity is checking event scoreboard, and at least thanks for making it actually work. (Whoever doesn't know, only in 3.8 they have fixed the scoreboard to display everyone's scores rather than only your own.) Now, as soon as the coalition event ends, the event scoreboard immediately stops being accessible. But coalition leaders need to know who scored in the event. I propose to make coalition scoreboard available in coalition interface for at least 24 hours past the event end.

This can be extended to have a month-long list of past events with their coalition scoreboards available to view, however this will take some toll on the database storage capacity.