OpenSystemsDevelopment / qpdf

Most of the README files have been renamed. Refer to the new names.

Slightly improve memory cleanup in Pl_DCT
Make it easier to test with valgrind

While scanning the file looking for objects, limit the length of
tokens we allow. This prevents us from getting caught up in reading a
file character by character while digging through large streams.

A stray semicolon caused a condition to be incorrectly applied during
stream length recovery.

Pushing member variables into a nested class enables addition of new
member variables without breaking binary compatibility.

Reduce code duplication

Remove duplicated coverage cases from Sahil's code so existing test
suite passes.

* Add support for PCLm using setPCLm() and writePCLm() methods in
  QPDFWriter.hh and QPDFWriter.cc
* Add a function writePCLmHeader() for PCLm header in QPDFWriter

There is no need for a --precheck-streams option. We can do the
precheck without imposing any penalty, only re-encoding the stream if
it fails the first time.

This commit adds several API methods that enable control over which
types of filters QPDF will attempt to decode. It also adds support for
/RunLengthDecode and /DCTDecode filters for both encoding and
decoding.

Additional testing is added in later commits to be supported by
additional changes in the library.

Add a newline unconditionally before endstream even if a newline was
already written as part of the stream data.

Bad /W in an xref stream could cause a division by zero error. Now
this is handled as a special case.

Rather than checking consistency of libqpdf.map, generate it.

The build now checks to make sure libqpdf.map has the right library
version number in it.

Also accept more errors than before.

Eliminate PCRE and find endobj not preceded by endstream. Be more lax
about placement of endstream and endobj.

Preparing to refactor some pattern searching code to use these instead
of their own memchr loops. This should simplify the code that replaces
PCRE.

Sometimes we want to ignore bad tokens rather than having them throw
an exception. A coverage case is commented out here and added in a
later commit.