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++

Do not segfault when trying to send TLS data over a not-yet connected socket

Avoid leaking socket filedescriptors

When trying the various results of getaddrinfo, we forgot to close the
socket when one fails, before trying the next one.

Also use the destructor to make sure we do not have some other unrelated
leak.

Add verifyCert field into the database

Only include the coverage flags when compiling with gcc

Fix a clang warning

Add a CI build with clang

Make the CA file configurable

Provide an adhoc option to let user pass the cert verif for some IRC servers

Fix the build without botan, caused by credentials_manager

Verify TLS certificate with the given hostname, instead of a hardcoded one