Primarily the getUrl call is fixed. Also some new class calls

Primarily the getUrl call is fixed. Also some new class calls

The getUrl call would think that a File_thumbnail object was the child
of a local File if its filename was set. That has been true up to recent
development code where a File_thumbnail can have a 'filename' value,
but the original File does not. Only look at the File object to indicate
whether it's a local or remote file!