qulogic/pidgin

Add a cancellable property to PurpleConnection and port IRCv3 to it

As more and more of our protocols start using Gio, it just makes sense to have
a cancellable ready for them.

Testing Done:
Connected, disconnected, and reconnected and IRCv3 account without issue.

Reviewed at https://reviews.imfreedom.org/r/2864/
subdir('reference')
if ENABLE_GTK
configure_file(
input : 'pidgin3.1.in',
output : 'pidgin3.1',
configuration : man_conf,
install : true,
install_dir : get_option('mandir') / 'man1')
endif
if enable_consoleui
configure_file(
input : 'finch3.1.in',
output : 'finch3.1',
configuration : man_conf,
install : true,
install_dir : get_option('mandir') / 'man1')
endif