Properly search for libbotan even in a botan-1.11 subdirectory

Convert \n to <br/> in xhtml body

fix #2539

Give two supported compilers, as examples

Document the new optional libbotan dependency

Implement TLS support using Botan

For now, it tries two TLS ports and then connects to the non-tls port.  In
the future we would like the user to be able to configure that.

fix #2435

Little doc fix

Make the destructor of the SocketHandler class protected non-virtual

Update the documentation

Do not send an item-not-found presence from an invalid JID

Remove some unused function parameters names

Document the `admin` configuration option

Add an ad-hoc command to disconnect some users

Add the libuuid dependency to the INSTALL file

Send (every 240s) a PING command to all connected irc servers

fix #2452

TimedEventsManager is now a singleton

Timed events can have a name, and can be canceled based on their name

Use libuuid to generate unique IDs for iq and adhoc sessions

Use pkg-config first to find libraries

Add missing files (for adhoc command support)

XmlNode::get_children, to get a list of matching children instead of the first