Implemented toTimelineTime
Added unit test. Refactored Timeline to incorporate
understanding of zero time.
Renamed unit test -> impl test.
Adding a test to check direction="alternate".
Merge pull request #239 from rjwright/toTimelineTime

Implemented toTimelineTime
Removing test-preset-timings.
Merge pull request #244 from mithro/fix-preset

Removing test-preset-timings.
Merge pull request #240 from mithro/test-alternate

Adding a test to check direction="alternate".