Implement _NET_WM_STATE_STICKY, bound to CM-s by default; allows any

client to 'stick' to all desktops (ewmh speak) or groups - this
currently has the same affect as setting a client's group to 'nogroup',
with the exception that the client can also be in a group, so when
un-sticking, the client will go back to its original group/desktop.

cwmrc.5

@@ -14,7 +14,7 @@
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.Dd $Mdocdate: December 16 2013 $
+.Dd $Mdocdate$
 .Dt CWMRC 5
 .Os
 .Sh NAME
@@ -341,6 +341,8 @@ Raise current window.
 Label current window.
 .It freeze
 Freeze current window geometry.
+.It sticky
+Stick current window to all groups (same as assigning to nogroup).
 .It fullscreen
 Full-screen current window (gap + border removed).
 .It maximize