Use the configured encoding value when decoding received messages

Defaults the encoding in the DB to latin-1

Also provide in and out encoding configure options for IRC servers

Add an ad-hoc configure command on IRC channels

Include encodingIn and encodingOut options, unused at the moment

Add a ChannelOptions table in the DB

And a way to retrieve its values, defaulting on the ServerOptions for unset
values.

A few cleanups, and make a few things more modern

Notify systemd when the process is stopping

Also store a reference instead of a pointer, in AdhocCommandsHandler

Use references instead of raw pointer, to store the “parent” object

In Bridge and IrcClient

Make the XMPP server address configurable.

fix #3145

Add an ad-hoc command to disconnect a user from one or more IRC server

fix #3077

JID class provides bare() and full() methods

Small cleanup

Provide a “var” map in AdhocSession objects, to save values between each step

Do not forget to call freeaddrinfo, fix a memleak

For the getaddrinfo call we added in the previous commit, to convert the IP
provided in the conf.

Display a better error when connection fails

The error should not tell “while reading” when we are just connecting.

Add the outgoing_bind option

Lets the admin choose a local address to bind each outgoing (IRC) socket.

Document the fact that the joining-nick is ignored

fix #2695

Rename the CI build where we run the coverage

Coverage cannot run with clang++