We need to improve the comments explaining the main ideas / insights of the solution

Regressed in DMOJ/judge-server#673, since now the cache is per-worker-process, and gets destroyed on exit. Will require a rewrite of the caching system.

Is your feature request related to a problem? Please describe.

Now we need to manually click "Uncheck Accepted" in the "More" menu of the test cases. Some users may want to automate this process.

Describe the solution you'd like

Add an option to auto-uncheck accepted test cases.

In #549, we added unittests for dispatch AtCoder and Codeforces.
To increasing test coverage, we should add unittests for other contest (HackerRank, CS Academy, ...).

Not only tests for all other contests, tests for the part of contests are welcome.

https://github.com/DOMjudge/domjudge/blob/3f8c8b1f8d69c142ea90d34653c55a2c07d195c7/sql/files/examples/boolfind_cmp/run#L9

The above file and the manual from October 2017 mentioned the existence of a teammessage.txt feedback file that, presumably, would be shown to the team as submission feedback like judgemessage.txt is shown to the judges.

I have recently had cause to desire this functi