Feature Request: add "--recursive" option in `shred` command

[Evan Greenup]

Currently, `shred` can securely wipe single file without remaining any 
recoverable data on the storage, while `rm` can only un-link the file.

However, `rm` is capable to remove files recursively, with "-R/"--recursive" 
flag, it is able to remove entire specific directory tree.

It would be awesome, if it support "-R" flag, which can wipe whole directory 
tree, include shred file content, rename files and folder names with random 
string.

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