This patch makes use of the recently added support for const RPC
functions by turning 'Framebuffer::Session::mode()' and
'Input::Session::is_pending()' into const functions.
The 'mode_sigh' function allows the client to receive notifications
about server-side display-mode changes. To respond to such a signal, the
client can use the new 'release' function, which acknowledges the mode
change at the server and frees the original framebuffer dataspace. Via a
subsequent call of 'dataspace', a framebuffer dataspace corresponding to
the new mode can be obtained. Related to issue #11.
Norman Feske
Genode Labs