Rename milestone_type to goal_ticket_type.  Refs #9648.
Rename milestone_type to goal_ticket_type.  Refs #9648.

Trying to eliminate confusion about what a "milestone" is.

git-svn-id: 2159781fc7c14c6bdd1f7e265daf7a25099c31e7@12323 7322e99d-02ea-0310-aa39-e9a107903beb

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