Back to Authors and Users link redirects to the wrong screen

[PeteMall]

When you edit a user from network admin site-users screen, the "← Back to Authors and Users" link redirects the user to the network/users.php instead of network/site-users.php?id=x

[SergeyBiryukov]

Also, after editing a user on network/users.php the referer is empty:

/wp-admin/network/user-edit.php?user_id=4&updated=true&wp_http_referer

[SergeyBiryukov]

Fixed empty referer.

[nacin]

Looks good.

[nacin]

Final patch works for me. Modified the URL generation a bit -- network_admin_url() and full esc_url() -- and in user-edit, we're now only adding the wp_http_referer argument if there is one, preventing a URL that looks like:

user-edit.php?user_id=2&updated=true&wp_http_referer

Tested every way possible. Offering commit.

[nacin]

(In [17201]) Allow us to return from whence we came. Specify wp_http_referer for user-edit in the network admin, as we may come from network/users or site-users. props PeteMall, SergeyBiryukov, fixes #16053.