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 new d3m component is the designated device-driver manager for the
upcoming live CD. It addresses the auto probing of USB storage and ATAPI
boot devices (issue #94) and the aggregation of user input coming from
USB HID and PS/2.
As a preliminary step for working on issue #11, this patch revisits the
'Framebuffer::info' RPC call. Instead of using C-style out paramters,
the new 'mode()' RPC call returns the mode information as an object of
type 'Mode'. Consequently, mode-specific functions such as
'bytes_per_pixel' have been moved to the new 'Framebuffer::Mode' class.
This patch changes decouples the conversion of the terminal state to
pixels from the write RPC function. Intermediate terminal states
produced by sub sequential write operations do not end up on screen one
by one but only the final state becomes visible. This drastically
improves the speed of scrolling through large text output.
