#417774: Add Public FileField API Functions and fix field_file_references() to not be field specific.

#333994 by Grunog2, Not setting file permissions on uploads.   set perms to 644 after file_save_upload in field_file.inc

#319114 by pasqualle, fix notices in field_file_save_file using variable names copy and pasted from field_file_save_upload.

add field_file_references($file, $field) to load references by field.
rename $item['filefield_delete'] to more descriptive $item['field_name'].

Note that the 5.x revision bug (#263162) does *not* appear anymore. Whoo!

Also, for consistency, files are converted to objects (and back, in case)
every time they are passed to other modules.

Plus the usual minor cleanups and documentation fixes.

(load, save_upload, save, delete).

'insert' and 'update' hooks for hook_file().

Also make sure that we can pass by reference in any case (so that modules
can insert properties on $op = 'load'), and adapt some style bits to
core's style conventions.

Don't expect anything usable yet - it works, but still has a long way to go.

Thanks a lot to Crell for getting this thing rolling.

and Crell's D6 patch at issue #269073. filefield.module is not yet being
committed though, I don't feel like it's ready even for a -dev version
in the current state. Regard this commit as move to make it easier to work
on the #269073 patch.