doc_save reported "incremental": !full, from the arguments alone. When
an in-place save had to be a full rewrite (after doc_protect adds or
removes encryption, or after Sanitize), write_incremental fell back to
write_full, but the result still said the save was incremental.
The result now says whether the written file starts with the file it
was saved over, read from the new Document::saved_bytes. An ordinary
in-place save still reports true and an explicit full save false.
Adds an_in_place_save_reports_a_required_rewrite_as_not_incremental,
which fails before this change for both doc_protect and
doc_remove_hidden.
Marco Arnulfo
77c3f2003a