IORedir
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Please refer to the document [IORedir Check Type](http://judge-hypex.readthedocs.io/en/latest/TestOJCompatible.html#ioredir-check-type) for how to package IORedir problems.

Diagram
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(*1) You can set the test program's `pipeout` to an `arbitrary file descriptor (e.g. 100)`, and also set the checker's `pipeout` to an `arbitrary file descriptor (e.g. 200)`. Write a loop in the checker to read `pipeout (e.g. 200)` until reaching EOF. The EOF indicates that the test program has closed the `pipeout file descriptor`, which means the test program has exited.

Example 1
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[checker.cpp](https://gist.github.com/pzread/58ae42f7f51347e0b2d11acdc3715aee#file-check-cpp)
[Json config](https://gist.github.com/pzread/58ae42f7f51347e0b2d11acdc3715aee#file-conf-json)
[Problem package](https://github.com/pzread/judge/tree/master/tests/testdata/res)

In this example, file descriptors of the test program are configured as:

0 (standard input): Test input file.
1 (standard output): Pipe to the checker.

File descriptors of the checker are configured as:

0 (standard input): Pipe from the test program.
2: Test answer file.

Therfore, checker can read the test program's output from its `stdin`, and read the answer from `file descriptor 2`. It will compare them, and if there is any difference, exits with -1 (wrong answer).

If you are creating an interactive problem, be sure that both the test and checker use `setvbuf` to disable the output buffers. Otherwise the pipes could cause deadlock.

Example 2
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TBD