Now that ReSharper supports it (see https://youtrack.jetbrains.com/issue/RSCPP-14653)
* Rewriting Timeline<T> to be sparse, i.e., allow gaps * Added specialized subclasses BoundedTimeline<T> and ContinuousTimeline<T> * Timed<T> and TimeRange: has-a, not is-a * Introducing Timed<void>