The "dir" key is used within the public sharing template to indicate in which directory the user currently is when sharing a directory with subdirectories. This is needed by the JS scripts.

However, when not accessing a directory then "dir" was set to the relative path of the file (from the user's home directory), meaning that for every public shared file the sharee can see the path.
(For example if you share the file "foo.txt" from "finances/topsecret/" the sharee would still see the path "finances/topsecret/" from the shared HTML template)

This is not the excpected behaviour and can be considered a privacy problem, this patch addresses this by setting "dir" to an empty key.

$file only contains the filename and not the absolute path, that means that files in a subdirectory will not get properly resolved and an empty filesize is returned.

This feature only exists on master.

We don't support direct updates from older ownCloud versions except the previous one therefore this code is unused and can be removed.

fixes download issue introduced by #10755

Conflicts:
	apps/files_sharing/public.php

This fixes an issue when a subdir has the same name as its parent, it
would get exluded from the list.

* otherwise it will always think it hits the limit and need another round to fetch additional results

ownCloud passes us a Unix time integer, but the GDrive API wants
an RFC3339-formatted date. Actually it wants a single particular
RFC3339 format, not just anything that complies will do - it
requires the fractions to be specified, though RFC3339 doesn't.

This resolves issue #11267 (and was also noted by PVince81 in
reviewing PR #6989).

the real file and the part file, because some information from the part file
might be needed later