Move all constructors at the top of classes

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

fix #3175

[ci skip]

We can now insert steps between the two parts

fix #2

Avoids:

- Relying on github’s services
- Fetching a new (malicious) version, automatically, without any “check”