Enable to have more subfolders
When a lot, really a lot of files are stored in current implementation we managed to make it fail due to filesystem limitation of number of files in a folder.
One simple to go beyond is to enable to have more subfolders. Either by configuring the number of characters to be used for first level (currently only 1, which result with 16 sub folders at the top, using 2 will result with 256 two letters folders) or by configuring the number of subfolders hierarchy (using 2 will result of 16 subfolders inside each of the 16 subfolders).