Show a competitors completed challenges

[Sch3lp]

Why this feature
As a competitor I'd like to know on which challenges I can still beat my opponent, or how far ahead they are (i.e. have they completed a whole bunch of low point challenges, and do they still have one big one to go, or did they complete one big challenge?);
How many points can my opponents still get?

Tasks

• Clicking on a Competitor in the scoreboard shows a dialog of completed challenges (name + points)