Scheduler more flexible about missing/defaulted options.  Refs #9648.
Scheduler more flexible about missing/defaulted options.  Refs #9648.

The Gantt chart passes a bunch of options that come from the macro
invocation or the chart configuration in Trac.ini.  A lighter weight
client -- like the ticket change listener -- may not have all those
options and just wants default behaviors.  Some missing values weren't
handled as defaults before.

git-svn-id: 2159781fc7c14c6bdd1f7e265daf7a25099c31e7@12754 7322e99d-02ea-0310-aa39-e9a107903beb

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