Instead of LibGUI and WindowServer building their own copies of the drawing
and graphics code, let's it in a separate LibDraw library.
This avoids building the code twice, and will encourage better separation
of concerns. :^)
Previously we were rendering the whole menubar on every compose(),
even if nothing changed about it. Now it's in its own window and can
be invalidated and painted separately.
d66fa60fcf introduced the use of a timer
to coalesce screen updates. This is OK, but it does introduce update
latency.
To help mitigate the impact of this, we now have a second (immediate)
timer. When a compose pass is first triggered, the immediate timer will
allow the compose to happen on the next spin of the event loop (so, only
coalescing updates across a single event loop pass). Any updates that
trigger while the delayed timer is running, though, will be delayed to
that (~60fps) timer.
This fixes#103.
