OpenSystemsDevelopment / qpdf

Also, silently fix any angle that is a multiple of 90.

Refactor QPDFWriter::writeObjectStreamOffsets

Rather than converting each (sequential) object id to a string,
generate a string for the first id and than increment the digits in the
string.

Add new CLI Option --remove-structure

... to remove the /Root /StructTreeRoot and /MarkInfo entries.

Tune QPDFWriter writes to Pl_Count

... and use it in QPDFWriter and QPDF::generateHintStream.

Also, remove redundant QPDFWriter::writeBuffer.

Also,
- use Pl_Discard when only checking whether stream is filterable
- get last char directly from output string

Fix parsing of object streams containing objects with no white-space between them

... containing objects with no white-space between them.

To enforce the rule that objects end at the start-offset of the next
object, each object is parsed in it own object stream.

To facilitate this, a new private API input source is::OffsetBuffer has
been added which only contains the object but reports offsets relative to
the start of the object stream. This is adapted from OffsetInputSource by
changing the direction of the offset, endowing it with its own
BufferInputSource and striooing out checks duplicated in BufferInputSource.

Fixes the expected failure in the test case added in #1266.

Refactor calls to QPDFParser::parse

Add static parse methods. Make all external access to QPDFParser through
static methods.

Make all non-static methods including constructors private.

Refactor QPDF::resolveObjectsInStream

Only build strings when needed.

... to QPDFObjectHandle_private.hh

Fix object stream error/warning messages reporting wrong object id

This was due to the use of last_object_description, which is not set for
the object stream itself.

Also, modify the messages introduced #1391 and #1392 to report the supposed
offset of the objects.

Refactor writing of object streams

Cache output of pass 1.

Fix #1394

Move methods responsible for loading or keeping track of objects to
QPDF_objects.cc.

The split was part of the reverted #1297. Reintroducing it now makes it
easier/safer to keep the work to refactor the xref and object tables in
sync with main.

Also, add reverted #194 to .git-blame-ignore-revs.

This reverts commit bb045907a043b5c6de9fb804ff11087333747329.

Split QPDF.cc into QPDF.cc and QPDF_objects.cc

Move methods responsible for loading or keeping track of objects to
QPDF_objects.cc.

The split was part of the reverted #1297. Reintroducing it now makes it
easier/safer to keep the work to refactor the xref and object tables in
sync with main.

Refine recovery from missing startxref (fixes #1335)

Refactor xref table reconstruction (Fixes #1362)

Refactor InputSource