CopyDir recursively copies all files and directories in the from directory into the to directory. If the to directory does not exist, it is created.
EscapeFilename replaces bad characters in a filename with safe equivalents. The only character disallowed on Unix systems is the path separator "/". Windows is more restrictive; banned characters on Windows are listed here: https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx