Implement floating (please test and find bugs)

Details which are missing: A command to hide/show all floating clients,
moving/resizing clients with your mouse holding Mod1 (click anywhere
in the client, not just on its borders), resize/move by keyboard, select
next/previous client by keyboard

include/floating.h

@@ -0,0 +1,37 @@
+/*
+ * vim:ts=8:expandtab
+ *
+ * i3 - an improved dynamic tiling window manager
+ *
+ * (c) 2009 Michael Stapelberg and contributors
+ *
+ * See file LICENSE for license information.
+ *
+ */
+#ifndef _FLOATING_H
+#define _FLOATING_H
+
+/**
+ * Enters floating mode for the given client.
+ * Correctly takes care of the position/size (separately stored for tiling/floating mode)
+ * and repositions/resizes/redecorates the client.
+ *
+ */
+void toggle_floating_mode(xcb_connection_t *conn, Client *client);
+
+/**
+ * Called whenever the user clicks on a border (not the titlebar!) of a floating window.
+ * Determines on which border the user clicked and launches the drag_pointer function
+ * with the resize_callback.
+ *
+ */
+int floating_border_click(xcb_connection_t *conn, Client *client, xcb_button_press_event_t *event);
+
+/**
+ * Called when the user clicked on the titlebar of a floating window.
+ * Calls the drag_pointer function with the drag_window callback
+ *
+ */
+void floating_drag_window(xcb_connection_t *conn, Client *client, xcb_button_press_event_t *event);
+
+#endif