Revise Lucky Dip

[jvyden]

As discussed on Discord.

Pretty much, we want a system that incentivizes people to play recent levels that haven't been played, or missed in the Newest category.

The new code should do something like this:

• Gather all levels uploaded within the 14 days. This is an arbitrary number and should be okay to tweak.
• Filter out levels with negative CR to remove the levels people didn't like.
• Filter out levels with a high CR. The cutoff should be calculated by taking the CR of the top 25-30 levels.
• Show this list to the user.
• After this list has been shown (whether the user has scrolled through it or the list is simply empty or too short), start appending random levels. This is to address people who like the old lucky dip behavior of showing random levels.