Deal better with BOX_SIZE != 58
This patch adds several fixes to make wmbubble work on Debian GNU/kFreeBSD.
In particular:
 - recognize GNU/kFreeBSD as an option in the Makefile
 - call init_stuff if __FreeBSD_kernel__ is defined instead of just __FreeBSD__
 - use sysctl instead of kvm_read for system_cpu; inspired by FreeBSD patch for
   wmcube-gdk by KOIE Hidetaka (http://lists.freebsd.org/pipermail/
   freebsd-ports-bugs/2008-January/135006.html)
Merge branch 'kfreebsd-fixes' of https://github.com/d-torrance/wmbubble into d-torrance-kfreebsd-fixes
Merge branch 'd-torrance-kfreebsd-fixes'
Update version number for FreeBSD fixes