Tpetra: Make CrsGraph MatrixMarket I/O memory scalable
Created by: mhoemmen
@trilinos/tpetra Epic: #769
MatrixMarket input and output (I/O) for Tpetra::CrsGraph currently gathers the whole matrix to Process 0 before writing it. This is not memory scalable. "Memory scalable" means that no single process has to store more than a small constant factor times the maximum per-process memory usage of the distributed data structure. See also #352 and #353.