Add support for _NET_WM_STATE_SKIP_PAGER and _NET_WM_STATE_SKIP_TASKBAR; eerily

close to cwm's 'ignore'.

Roughly based on an initial diff from Walter Alejandro Iglesias, but with
support for both Atoms and without cwm-based bindings.

conf.c

@@ -720,6 +720,8 @@ static char *ewmhints[] = {
 	"_NET_WM_STATE_HIDDEN",
 	"_NET_WM_STATE_FULLSCREEN",
 	"_NET_WM_STATE_DEMANDS_ATTENTION",
+	"_NET_WM_STATE_SKIP_PAGER",
+	"_NET_WM_STATE_SKIP_TASKBAR",
 	"_CWM_WM_STATE_FREEZE",
 };