There are both some good changes and some terribly hacky changes in this
commit.
- Server uses a different struct than client now for windows, so
arbitrary compositor things like effect parameters can be added
without having to rebuild everything. That's good.
- Client window structs no longer attempt to track or use window
locations. That's good.
- Windows do not destroy in response to the destory command, but rather,
a special animation is triggered; the end state for this animation
calls the actually window destruction code. That's a hack.
- Animations are based on rendered frames, not on time. That's a hack.
Also, sleep() as a function (implemented by way of nanosleep) and new
absolute and relative sleep system calls added to newlib.
[ci skip] I damn well know this is going to break CI.
