Add sortable_challenge and distributed_map code

- Add the sortable_challenge code based on commit 6e839cb1dca3bfdd75704a6fc959fbaed2bef92f
- Add the distributed_map code based on commit c2c6436938520cc38a17e6b554d5381f6f3bb2eb
- Make a few changes to the runme*.sh files and where the output data files are stored.
- Create README.md file explaining how everything works.