Implement kill-command to kill the current window, document it

include/i3.h

@@ -18,7 +18,7 @@
 #ifndef _I3_H
 #define _I3_H
 
-#define NUM_ATOMS 10
+#define NUM_ATOMS 12
 
 extern char *application_path;
 extern Display *xkbdpy;

include/util.h

@@ -46,5 +46,6 @@ void leave_stack_mode(xcb_connection_t *conn, Container *container);
 void switch_layout_mode(xcb_connection_t *conn, Container *container, int mode);
 void warp_pointer_into(xcb_connection_t *conn, Client *client);
 void toggle_fullscreen(xcb_connection_t *conn, Client *client);
+void kill_window(xcb_connection_t *conn, Client *window);
 
 #endif

include/xcb.h

@@ -46,6 +46,8 @@ enum { _NET_SUPPORTED = 0,
         _NET_WM_WINDOW_TYPE_DOCK,
         _NET_WM_DESKTOP,
         _NET_WM_STRUT_PARTIAL,
+        WM_PROTOCOLS,
+        WM_DELETE_WINDOW,
         UTF8_STRING
 };