Feature request: sort/filter by difficulty/subject/votes

[vEnhance]

I'm unsure what it's currently sorted by but some more dials here might be nice.

[howard36]

Currently it's sorted by newest problems first. Better sorting and filtering is the next feature I plan to implement. Specifically:

• Sort by newest/oldest
• Sort by most upvoted
• Sort by hardest/easiest difficulty estimate
• Sort by least testsolved
• Filter by subject
• Filter by locked/unlocked (a problem is "locked" if it requires testsolving, and you haven't started a testsolve attempt)
• Filter by archived/unarchived
• Filter by author (maybe with a special option for your own problems)

You should be able to apply multiple filters, but only one sorting method. If no sorting/filtering is specified, it would default to: "Filter all unarchived problems, then sort by least testsolved (to encourage testsolving every problem), and tiebreak by newest first"