Provide the “realname_customization” option

ref #3136

The realname is also saved as an IrcClient member

TIL std::string::end and std::string::begin…

Make sure the user-provided username does not contain spaces

Provide username and realname IRC server options

Used in the USER command when connecting to the IRC server, instead of the
first nick.

fix #3028

Fix two small warnings

Catch TLS exceptions, close the connection and inform the user of the error

Connection may be closed from our side too

Add a field (in the configure form) to specifiy an after-connect IRC command

Provide Ports and TLS Ports IRC-server ad-hoc options

This let any user choose which ports to use when connecting to the IRC
server. This also lets the user choose whether or not to force TLS usage (by
setting no non-TLS port).

fix #2731

Send a PASS IRC command if the “pass” config is sot by a user, on an IRC server

fix #3068

Introduce the configure ad-hoc command on irc servers

Provides two options for now, and they have no effect yet

Add Bridge::get_bare_jid

XmlNode::add_child can also take a copy of a node

Add an AdhocCommandsHandler to store commands specific to IRC servers

Store the target jid in the AdhocSession objects

Introduce an optional Database module

Uses litesql

Also a xdg_data_path

Create a xdg_path function

Trivial cleanup in irc_client.cpp