* Added a UUID field to TimelineMarker.
* Updated StreamBasedTimelineSource to read and write UUIDs. The current format
is compatible with the 1.x format, but support for the 1.x format is planned
to be deprecated for 3.x.
The UUID is added on the same line as the timestamp, with a `,` separating
the timestamp and the UUID value.
* Updated JDBLabsWebTimelineSource to use UUIDs to reconcile the different
timestamp entries (more reliable that using the timestamp value).
* SyncTarget now persists the remote timeline after pushing to it.
* Added SyncTarget.shutdown() to allow callers to signal the sync timer thread
to stop.
* Fixed a bug where a SyncTarget was added instanciated times.
* Removed superfluous ``signpost`` library used by ``HTTPBuilder`` for OAuth
support.
* Refactored JDBLabsWebTimeline to throw appropriate exceptions when problems
occur while communicating with the server.
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`.
