Merge branch 'rst'

First rst attempt

Test the execution of the hello command

e2e: possibility to extract a value from a stanza and reuse it in send_stanza

Use “using” instead of typedef

ci: Have two builds: on fedora and on debian

Add a Dockerfile for biboumi-test-debian

Do not use std::endl for each line when saving the conf file

Fix build with POLLER=POLL

Run e2e in a subdirectory and lighten the build artifacts

Style fix

Move all constructors at the top of classes

Update .gitignore

Change the name of the DB in the e2e tests

Include the Configure ad-hoc command on biboumi's JID  for fixed_irc_server

Because a jid like “freenode.example.org” is both the JID for the configured
IRC server, and biboumi’s JID.

fix #3175

Trivial cleanup

Add e2e tests for the ad-hoc listing on the server jid

Remove a forgotten comment

[ci skip]

Test the the virtual channel

tests: Split the connection sequence into two

We can now insert steps between the two parts

Add a Dockerfile to build a biboumi-test image