Correctly handle the usage of ! as a IRC user mode indicator

Since “!” is also the separator between the nickname and the user hostname,
having “!” as the user mode (e.g. !nick!~some@host.bla) would cause the nick
to be empty. Now we skip it if it is a valid user mode indicator.

mini reorder

[cmake] Do not print useless messages when an optional lib is not found

Forward iq version results to IRC

Correctly do the error handling when we receive an iq

Forward CTCP version request to XMPP

Implement next_id() to

Use epoll on linux by default, poll otherwise

Link with systemd instead of systemd-daemon

Add missing std::string_literals

Fix a little indentation

Use C++14 string_literals

Remove binary.hpp and use the c++14 feature 0b

Upgrade to C++14

Include the xhtml-im element in private messages too

The author name from messages from the server are now nicely formated

NOTICE from channels are displayed in the channel, with a green "[notice]"

Respond to a disco query the gateway jid itself

Fix the kick by correctly using the from and to attributes

Fix the CMakeLists.txt to correctly have -Ibuild/src/