OpenSystemsDevelopment / qpdf

Split reconstruction into two passes - scanning of input for objects and
insertion of objects into the xref table. This allows insertion to take
place in the usual reverse order and removes the need for a separate
insert_reconstructed method.

Create unresolved objects only for objects in the xref table (except during
parsing of the xref table). Do not add indirect nulls into the the object
cache as the result of a cache miss during a call to getObject except
during parsing or creation/updating from JSON. To support this behaviour,
add new private methods getObjectForParser and getObjectForJSON.

As a result of this change, dangling references are treated as direct nulls
rather than indirect nulls.

Also add new fuzz test case.

Code failed to allow for QPDF::getCompressibleObjSet deleting objects
from the object cache in case of multiple entries for the same object id.

Add fuzz test case 68668.

Create set without creation of an intermediate vector.

Apply various Clang-Tidy rules

Using search and replace.

Set indent differently for qdf and non-qdf files.
Combine with preceding newline for qdf files.

Also, uninitialize QPDFWriter::Members members.

Use string_view parameters and call pipeline write methods directly.