…d by POSIX standard

(Including wrap_getpid.c which was absent)
Minor changes to student_code.h

The original code only made the reading end of the pipe non-blocking,
as it needs to empty the pipe after the sandbox.
But, if the student's program actually writes a lot on the writing end
of the pipe, the pipe will block and cause the program to timeout.
It is better to actually report this error (too much output)
rather than waiting for the task to end.
In both cases, the output will be truncated and it will not pass the tests,
as we may expect the problem author to not require the student to output
more than 65536 bytes or so of data on stdout or on stderr.

…bypass the tests.

Also, makes sure to have a less undefined behaviour if the student
actually calls exit: it will predictably raise a SIGSEGV instead of
randomly not crashing instantly.

Functions: socket, bind, connect, accept, listen, recv (and al),
send (and al).
Currently only supports statistics
Also included: Some unit tests

Not well-tested, however

…ng on stdout and stderr

…use by wrap_file and wrap_socket

…socket

- Remove write-related functions from read_write (currently not needed).
- Add to run_ci the possibility of executing a single test.
- A few corrections in read_write (time.h, NULL, const etc).
- Allow exit to be called normally when the sandbox is not running.

Among these were incoherence between nanoseconds, microseconds and
milliseconds, bad type for intervals, and something else.
Functionnalities added include the possibility to create a read_buffer_t
from the tables of offsets and intervals, when the data is contigous.

… monitored

…above 50%

The function allows to connect a UDP socket to a remote client. Also, a
confusion has been fixed

Needs to be applied after read_write changes

- monitored.gai_strerror
- memory leak when reset
- missing implementations of setters of fai_report and check_fai
- Fix simple_getaddrinfo so that it is more compliant to the true one
- Add reset for all alternative methods