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

Check the number of argument of every IRC command received from the server

Each IrcClient callback has a max and min size of argument, we call the
callback only if the parsed message has a correct number of arguments,
otherwise it is ignored (with a warning logged).

Trivial cleanup

Use unique_ptr to store the XmlNode’s children

Also fix some constness things

Little cleanup of the XmlNode class

Use map instead of unordered map (it's not slower, and it's shorter).
Use the default move constructor.

XmlNode::to_string uses an ostringstream instead of a string

On my poor benchmark, it was infinitesimally faster.

XmlNodes are now always closed

Remove the close() method and closed attribute. Remove all the calls to
close().  (Save one bool per XmlNode, yay, and save a few ifs and some
useless function calls. At best it should be unnoticeably faster and lighter
and save a few keystrokes in the future)