a more advanced challenge mode
RC = start recording challenge
SC "path" = save current challenge to path
HINT "string" = add hint in current position
HINT ("string", x, y) = add hint in position(x,y) (no error checking
here now!)
RH = remove all hints
RH number = remove n-th hint(index could be found left to each hint)
QUIT = quit recording
Challenge "path" = load challenge from path
HINT show/hide hints
QUIT = quit playing