single instance of the IntervalManager unlike the standard Java Timer
services which would require someone to have a timer instance to do the
scheduling of our safe intervals. Plus Ray will be much happier now that
the SafeInterval is not so flippant about reusing methods.
git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@1392 542714f4-19e9-0310-aa3c-eee0fc999fb1
Andrzej Kapolka