Added `clear` command.
Refactor.
Added BaseContest class.
Removed `vis_params` argument from command's handle() function.
Don't send project object to mediator. Send only the most needed settings.
Added Scores class to keep track of the best score.
Added simple Contest class.
Added `single test` command.
Improved multitests output in simple contest.
Added `multi test` command.
Added `best` command.