hdf5_der

[svn-r25316] Brought up to current version I'm running (known by some as ...datasets2.c)
Usage is:
   printf( "Usage: %s [-c cols_per_row] [-w rows_per_write] [-r rows_per_read] [-b rows_per_rank] [-i num_iterations] [-p persist_rate] [-e] [-L] [-P] [-S] [-d] [-v] \n", app  );
   printf( "\tc: number of columns per row (each cell is 8 bytes)\n" );
   printf( "\tw: number of rows per write per rank\n" );
   printf( "\tr: number of rows per read per rank\n" );
   printf( "\tb: number of rows in each rank's block (if not multiple of w or r, may not be fully written or read)\n" );
   printf( "\ti: number of iterations to do writes/commit/[persist/evict/prefetch/reads/evict]\n" );
   printf( "\tp: persist rate; for /DP and /DS, also impacts evict/prefetch/read/evict\n" );
   printf( "\te: enable checksums on raw data in H5Datasets\n" );
   printf( "\tL: create /DL dataset - data will not be evicted (created by default if no /DP nor /DS)\n" );
   printf( "\tP: create /DP dataset - data will be evicted, replica prefetched, reads from replica\n" );
   printf( "\tS: create /DS dataset - data will be evicted, reads from storage (DAOS)\n" );
   printf( "\td: print detailed timing information for each read and write operation\n" );
   printf( "\tv: verbose output of data values - intended for use only with small arrays and few iterations\n" );

More changes to come, but wanted to get this one committed.