io.monitors.recursive: On Windows, at least, a recursive file monitor gets
set up for every single file. This is causing OOM errors on win32, so
let's just test resource:core\io instead.
colors.lab: add copyright.
colors.distances: implement CIE76, CIE94, CIEDE2000, and CMC l:c color difference algorithms.
io.monitors.recursive: fix second test.
colors.distances: add some tests, refactor locals a little bit.