Weight children's completion when calculating group completion.  Refs #9301.
Weight children's completion when calculating group completion.  Refs #9301.

It used to weight each child equally.  Now it accounts for each child's
estimate.

git-svn-id: 2159781fc7c14c6bdd1f7e265daf7a25099c31e7@10827 7322e99d-02ea-0310-aa39-e9a107903beb

trac-hacks/trac-jsGantt,trac-hacks/trac-jsGantt,trac-hacks/trac-jsGantt