Round related commands

This is an advanced version of .match command where you can customize the following:

1. Number of participants (Upto 5)
2. Number of problems (Upto 6)
3. Ratings of problems (From 800 to 3600 inclusive)
4. Points of problems (From 100 to 10,000 inclusive)
5. Whether you want a new problem to appear when someone solves a problem.
6. List of alts ( Upto 5)

Commands:

• .round challenge @user1 @user2...: Challenge someone to a round. Note: You can challenge up-to 4 different users during a round.

• .round update: Trigger bot to update rounds for a server. Note: Can be used once in every 20 seconds per server.

• .round problems @user: View the problem of someone's round. Note: user is an optional field.

• .round ongoing: View list of ongoing rounds.

• .round recent @user: View list of recent rounds. Note: user is an optional field.

• .round invalidate: Invalidate your round.

• .round _invalidate @user: Invalidate someone's round. Note: Can be only used by users with Admin privileges as discussed here.