pio2.5.7

What's Changed

• remove the redefinition of MPI_Offset and MPI_OFFSET by @jedwards4b in #1916
• update minimum cmake version, based on the oldest I can access by @jedwards4b in #1920
• parallel sort by @jedwards4b in #1921
• closer to requred cmake minimum by @jedwards4b in #1922
• update version to 2.5.7 by @jedwards4b in #1923

Full Changelog: pio2_5_6...pio2_5_7