OpenSystemsDevelopment / qpdf

This improves indentation of long strings. This commit also fixes some
trailing whitespace in ChangeLog.

This requires a special build option.

Change QPDFWriter stream_decode_level default to qpdf_dl_generalized (fixes #1286)

Also, fix disabling of preserve_encryption to be ignore
stream_decode_level, but disable preserve_encryption if compress_streams is
false.

Fixes #1286

Handle case where named destination is a dictionary with /D entry.

Test case is hand-edited outlines-with-old-root-dests.pdf with modified
object 107.

Alternative clean dct fuzz changes

Previous test case was lost in #1221. Test file was created from
object-stream.pdf by adding a reference to itself into object stream 1 0.

The code accepted values other than /Yes but still used /Yes as the
checked value instead of obeying the normal appearance dictionary.

...as well as some cases generated in CI from earlier attempts at
fixing this.

Holding release to think about recently discovered incorrect handling
of deleted generations.

This reverts commit 162716807c475498dfbecc89fd222fb6c45d70c9.

...when flattening annotations. This includes /Link, /Popup,
and /Projection.

Rather than adding yet another flag that is almost never useful on its
own, just have --remove-restrictions disable digital signatures. The
operations are still separate in the API.