Added necessary XInitThreads() call

Hello,
I am using Xubuntu OS and I am met the following error while using your library:
"[xcb] Unknown sequence number while processing queue
[xcb] Most likely this is a multi-threaded client and XInitThreads has not been called
[xcb] Aborting, sorry about that.
mktrayicon: xcb_io.c:274: poll_for_event: Assertion `!xcb_xlib_threads_sequence_lost' failed."
I am searching the decision and find the following suggestion:
http://stackoverflow.com/questions/18647475/threading-problems-with-gtk
I suppose, that decision above should be added to the master branch.
Thank you for your attention.