Hustoj essay 8-on-demand download of the test data on the judgement Terminal

Today, we developed a test data distribution system. This idea was first proposed by freefcw or seflat during group discussions. The details are unclear.

1. Extends the admin/problem_judge.php function to provide the file list and specified file content in the data directory.
2. Added the get_test_file function in http_judge mode in judge_client to get the list and files.
3. Compile a special referee when the file is SPJ. c/SPJ. CC.

Finally, when the question end lacks test data, it can directly download the test data from the web, without having to copy a large amount of test data in advance, facilitating dynamic addition of the judge client.

During the test, it is found that the network is unstable and data may be damaged. If you have time to perform md5sum, we recommend that you use this function only in a stable and reliable LAN.