Add gatherv wrapper to Teuchos
Created by: mhoemmen
@dridzal requested a gatherv wrapper for either Teuchos or Tpetra. Tpetra has an implementation of this wrapper now, but it currently lives in an anonymous namespace. @dridzal would like to see it promoted to the public interface. See commit b5b1b8f0.
It would be easy for just about any Trilinos developer without much Tpetra or Teuchos knowledge to promote Tpetra's current internal implementation to a public interface, and add a unit test. I'll be happy to review and accept pull requests.