MCPL release 2.2.0

This minor release adds a few new functions to the C API with utilities meant to make life easier when implementing MCPL bindings in downstream applications (#91).

• Two new functions mcpl_create_outfile_mpi and mcpl_merge_outfiles_mpi can be used to handle some of the tedium and book-keeping needed for applications creating multiple MCPL files from a number of MPI processes before finally merging to a single file.
• The mcpl_name_helper function helps with parsing user input MCPL filename parameter strings into absolute or relative path names, with or without a .mcpl or .mcpl.gz suffix.

Like all other functions in the MCPL C API, these new functions work on both POSIX and Windows systems and can handle unicode characters in file-system paths. Refer to comments in mcpl.h for more information (here).

Full Changelog: v2.1.0...v2.2.0