pidgin/pidgin

Use G_DECLARE_DERIVABLE_TYPE for PurpleConversation and additional cleanups

The setters for PurpleConversation are kind of crappy because of the
conversation cache in the purple_conversations api, which we'll address at a
later time.

Testing Done:
Compiled and ran locally, parted a chat and just signed out to verify no new issues.

Reviewed at https://reviews.imfreedom.org/r/613/
subdir('disco')
subdir('gestures')
subdir('xmppconsole')
if PLUGINS
gtkbuddynote = library('gtkbuddynote', 'gtkbuddynote.c',
dependencies : [libpurple_dep, libpidgin_dep, glib],
name_prefix : '',
install : true, install_dir : PIDGIN_PLUGINDIR)
iconaway = library('iconaway', 'iconaway.c',
dependencies : [libpurple_dep, libpidgin_dep, glib],
name_prefix : '',
install : true, install_dir : PIDGIN_PLUGINDIR)
notify = library('notify', 'notify.c',
dependencies : [libpurple_dep, libpidgin_dep, glib],
name_prefix : '',
build_by_default: false,
install : false, install_dir : PIDGIN_PLUGINDIR)
relnot = library('relnot', 'relnot.c',
dependencies : [libpurple_dep, libpidgin_dep, libsoup, glib],
name_prefix : '',
install : true, install_dir : PIDGIN_PLUGINDIR)
spellchk = library('spellchk', 'spellchk.c',
dependencies : [libpurple_dep, libpidgin_dep, glib],
name_prefix : '',
build_by_default: false,
install : false, install_dir : PIDGIN_PLUGINDIR)
if IS_WIN32
transparency = library('transparency', 'transparency.c',
dependencies : [libpurple_dep, libpidgin_dep, glib],
name_prefix : '',
build_by_default : false,
install : false, install_dir : PIDGIN_PLUGINDIR)
endif
if enable_unity
unity = library('unity', 'unity.c',
dependencies : [UNITY, libpurple_dep, libpidgin_dep, glib],
name_prefix : '',
install : true, install_dir : PIDGIN_PLUGINDIR)
endif
endif # PLUGINS