huge change: implement RandR instead of Xinerama

Thanks to Merovius for doing a proof of concept on this one and
being a driving force behind the idea.

Using RandR instead of Xinerama means that we are now able to use
the full potential of the modern way of configuring screens. That
means, i3 now has an idea of the outputs your graphic driver
provides, which allowed us to get rid of the ugly way of detecting
changes in the screen configuration which we used before. Now, your
workspaces should not be confused when changing output modes anymore.

Also, instead of having ugly heuristics to assign your workspaces
to (the screen at position X or the second screen in the list of
screens) you will be able to just specify an output name.

As this change basically touches everything, you should be prepared
for bugs. Please test and report them!

include/handlers.h

@@ -3,7 +3,7 @@
  *
  * i3 - an improved dynamic tiling window manager
  *
- * (c) 2009 Michael Stapelberg and contributors
+ * © 2009-2010 Michael Stapelberg and contributors
  *
  * See file LICENSE for license information.
  *
@@ -11,6 +11,8 @@
 #ifndef _HANDLERS_H
 #define _HANDLERS_H
 
+#include <xcb/randr.h>
+
 /**
  * Due to bindings like Mode_switch + <a>, we need to bind some keys in
  * XCB_GRAB_MODE_SYNC.  Therefore, we just replay all key presses.
@@ -74,6 +76,14 @@ int handle_map_request(void *prophs, xcb_connection_t *conn,
  */
 int handle_configure_event(void *prophs, xcb_connection_t *conn, xcb_configure_notify_event_t *event);
 
+/**
+ * Gets triggered upon a RandR screen change event, that is when the user
+ * changes the screen configuration in any way (mode, position, …)
+ *
+ */
+int handle_screen_change(void *prophs, xcb_connection_t *conn,
+                         xcb_generic_event_t *e);
+
 /**
  * Configure requests are received when the application wants to resize
  * windows on their own.