Tpetra::Crs{Graph,Matrix}: Add local_offset_type typedef
Created by: mhoemmen
@trilinos/tpetra Per request by @kddevin (see #674 (closed) discussion), add a local_offset_type typedef to Tpetra::CrsGraph and Tpetra::CrsMatrix. This type tells users the type that Tpetra uses to store row offsets, in the local sparse graph / matrix. The local_ prefix makes it clear that this refers to the local data structure.