Rename to Remoh

Closes #32

Due to possible legal issues with the use of «Homer» to refer to the
project and the tool, it has been decided to change the name into Remoh.

[DoT] Catch closed connection

See merge request bortzmeyer/homer!30

Calculate the elapsed time per query based on the number of finished
queries and not the number of wanted queries.

Based on OpenSSL manual and pyOpenSSL documentation, a closed connection
raises an error SSL_ERROR_ZERO_RETURN which raises a ZeroReturnError
exception.
See <https://www.openssl.org/docs/man1.1.0/man3/SSL_get_error.html> and
<https://www.pyopenssl.org/en/stable/api/ssl.html#OpenSSL.SSL.ZeroReturnError>

Do not exit on error with --check

See merge request bortzmeyer/homer!28

The error() function should be used to diplay an error message. If the
program should exit after printing the error message, use
error_and_exit() function instead.

Improve --check

* refactor
* better output (number of resolved IPs, error after test status)
* new mandatory level : `nocrash`

See merge request bortzmeyer/homer!27

This is to use with tests that are not documented in the RFC and where
the response of the server is unknown. We think it is good that the server
do not crash when facing those tests.

and output IP on error

Use level of 30 (legal) for the truncated check in order to avoid
regression with the tests.

Do not return any state from the print_result method. The success's
state should already be known when calling this method.