[wmii] No-bars pull request

Hello there!

People seemed to be interested in a no-bars pull request, so I hacked
something up. You can disable framebars via /ctl (framebars 0|1), and
disable the bar with the -b option given to wmiiwm. At most the bar
part is implemented pretty crappily, and wmii would need some less
refactoring and added features to have this feature in somewhat clean
code. (I suppose less EWMH.) Whatever. Enjoy it!

Denis