Be less strict on rom directories structure

[sveetch]

Some people like to organize their rom systems directories with sub-directories to categorize, or just have less listed files.

Actually the manager interface is not able to follow sub directories.

[sveetch]

1. List sub directories
2. Clickable sub directories to get into them;
3. View have to remember from what system it come from when walking into sub directories;
4. Upload and delete form should be aware of real current path to do their action in the right place;