TicketLinks: Add setter to disable ticket links. By default, ticket links should be created.
Comment/DowntimeRenderer: Add setter noObjectLink()
CommentRenderer: Add setter noSubjectLink(), only used for the comment-popup
TicketLinkObjectList: This class creates object list with ticket links using TicketLinks trait
CommentRenderer: Defines the rendering rules for Comment object
Cleanup css and unused classes
Adjust comment-popup.less