Preliminary vplanet release

This version is nearly stable and complete. All examples of forward integrations have been validated and are part of our continuous integration tests. Documentation is still thin, and tidal heating of the Earth model has not been completed. Some memory leaks are still present, but none appears to be significant. Users should be confident in the results, but may want to wait for v1.0 before publishing any results based on vplanet, unless working with the VPLANET team.