COPY /U should allow for ignoring newly-added EAs

[Lewis Rosenthal]

When copying files to update a directory, if some files themselves are unchanged, they are copied anyway, simply because the source contains EAs where the target does not. The ability to ignore EAs when considering what is "new" would be useful, particularly when copying to destinations which do not support EAs (e.g., Samba shares), where such data will be discarded, anyway.

Transient EAs may exist on the source which are hardly relevant to the file content (consider kLIBC EAs or thumbnail images which are easily recreated). It would be more efficient to simply skip such files when updating the target directory. Note that I am not suggesting this as the default behavior, but rather an option.