Previous version only moved the VCP, causing "bogus pointer events" lateron.
Now we run through the device list, updating each pointer separately if
necessary.
Also stick a big warning into RRPointerMoved, not sure what device we need to
work on here.
Requires moving the spriteTrace into the DeviceIntRec and adjusting a few
functions to take in device argument, most notably XYToWindow().
Cursor rendering on the second screen is busted.
Add function to keep pointer within valid crtc areas.
Finish event delivery and swapping code.
Separate configuration from layout changes to send correct events.