Implement Xinerama (workspaces have a specific screen)

include/xinerama.h

@@ -0,0 +1,23 @@
+/*
+ * vim:ts=8:expandtab
+ *
+ * i3 - an improved dynamic tiling window manager
+ *
+ * (c) 2009 Michael Stapelberg and contributors
+ *
+ * See file LICENSE for license information.
+ *
+ */
+#include "data.h"
+
+#ifndef _XINERAMA_H
+#define _XINERAMA_H
+
+TAILQ_HEAD(screens_head, Screen);
+extern struct screens_head virtual_screens;
+
+void initialize_xinerama(xcb_connection_t *conn);
+i3Screen *get_screen_at(int x, int y);
+i3Screen *get_screen_containing(int x, int y);
+
+#endif