Handle explicit finish with implicit start in ASAP schedule.  Refs #9042, #9515.
Handle explicit finish with implicit start in ASAP schedule.  Refs #9042, #9515.

And vice versa in ALAP.

Also removed unnecessary fixup of explicit start; parseStart() already
zeros out those values.

git-svn-id: 2159781fc7c14c6bdd1f7e265daf7a25099c31e7@11084 7322e99d-02ea-0310-aa39-e9a107903beb

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