This patch introduces keyboard-focus events to the 'Input::Event' class
and changes the name 'Input::Event::keycode' to 'code'. The 'code'
represents the key code for PRESS/RELEASE events, and the focus state
for FOCUS events (0 - unfocused, 1 - focused).
Furthermore, nitpicker has been adapted to deliver FOCUS events to its
clients.
Fixes#609
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.
