Web timelines as defined by the JDB Labs Web TimeStamper tool are now supported.
* `TimelineSource` now also takes the timeline config file as constructor input.
* Refactored `Timeline` to use reduce implementation redundencies: internal
implementations do not duplicate functionality.
* Improved comments in `TimelineProperties`.
* Updated `TimelineSourceFactory` to handle timelines that need to use
`JDBLabsWebTimelineSource`.