This is the first step in the long-sought goal of allowing the window
size to change, but is required for passing on getting window position
and size information (though size is in viddef, it makes sense to pass
both together).
There's now an internal event handler for taking care of device addition
and removal, and a public event handler for dealing with device input
events in various contexts In particular, so the clients can check for
the escape key.
This has smashed the keydest handling for many things, and bindings, but
seems to be a good start with the new input system: the console in
qw-client-x11 is usable (keyboard-only).
The button and axis values have been removed from the knum_t enum as
mouse events are separate from key events, and other button and axis
inputs will be handled separately.
keys.c has been disabled in the build as it is obsolute (thus much of
the breakage).
For the mouse in x11, I'm not sure which is more cooked: deltas or
window-relative coordinates, but I don't imagine that really matters too
much. However, keyboard and mouse events suitable for 2D user interfaces
are sent at the same time as the more game oriented button and axis events.
