OpenSystemsDevelopment / qpdf

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.

Also fix a bug resulting from incorrect use of PointerHolder because
of this unused parameter.

Passed arguments to the constructor in the wrong order.

main() had gotten absurdly long. Split it into reasonable chunks. This
refactoring is in preparation for handling splitting output into
single pages.

This is added to contrib rather than examples because it requires
c++-11 and lacks a test suite, but it is still useful enough to
include with the distribution.

Required for strtol()

When parsing content streams, allow content to be split arbitrarily
across stream boundaries.

Be explicit about the need to keep the source QPDF object around.

The code was using 1.0, but we use /FlateDecode, which didn't appear
until 1.2.

Very badly corrupted files may not have a retrievable root dictionary.
Handle that as a special case so that a more helpful error message can
be provided.