Add rating filter and more

It would be extremely useful to have more filters such as

1. Show only the top rated problems (very useful when you come to a new sector with a lot of problems, I check this manually all the time…)

2. Show only the popular problems (say, with the number of logged ascents exceeding average; again, very useful when you are in a big sector and want to choose a nice problem)

3. Show only the problems climbed in the past period (month, year, custom period…)

This all would be very nice to have to simplify the exploration of new crags with a lot of problems…