CleanFilename strips all possibly suspicious characters from a filename WARNING: NOT suiteable for pathnames as slashes will be stripped as well!
CleanPath resolves common aliases in a path and cleans it as much as possible
IsDir checks if a certain path exists and is a directory https://stackoverflow.com/questions/10510691/how-to-check-whether-a-file-or-directory-denoted-by-a-path-exists-in-golang
IsEmptyDir checks if a certain path is an empty directory
IsFile checks if a certain path is actually a file
Shred overwrite the given file any number of times
Umask extracts the umask from env