Documenting how fws/xPapers works.

Unfortunately the documentation to xPapers is somewhat lacking. There is only an installation manual, the code is reasonably well commented but there is nothing to explain how everything fits together. Over the last few weeks we've been gradually working this out ourselves. To help anyone else who might use xPapers (and future employees on this project) we've begun to document what each file/directory does on our wiki at https://github.com/fws-hub/xPapers/wiki/File-Descriptions.