AthleteDirectory - Folder Structure Part 1

... introduce new "home" Folder structure object representing the
previous flat-folder
... adjust relevant QDir home - access to use the sub-folder method of
the new object

Note: the new structure is not yet active ! - everything is written to
the main folder still

To Do:
... add upgrade procedure for existing folder content to merge to the
new folders
Merge pull request #1103 from Joern-R/files

AthleteDirectory - Introduce Folder Structure Part 1