Log Message:
Update to 7.1.0

Changelog:
2018-01-14  Jay Berkenbilt  <ejb@ql.org>

	* 7.1.0: release

	* Allow raw encryption key to be specified in libary and command
	line with the QPDF::setPasswordIsHexKey method and
	--password-is-hex-key option. Allow encryption key to be displayed
	with --show-encryption-key option. Thanks to Didier Stevens
	<didier.stevens@gmail.com> for the idea and contribution of one
	implementation of this idea. See his blog post at
	https://blog.didierstevens.com/2017/12/28/cracking-encrypted-pdfs-part-3/
	for a discussion of using this for cracking encrypted PDFs. I hope
	that a future release of qpdf will include some additional
	recovery options that may also make use of this capability.

2018-01-13  Jay Berkenbilt  <ejb@ql.org>

	* Fix lexical error: the PDF specification allows floating point
	numbers to end with ".". Fixes #165.

	* Fix link order in the build to avoid conflicts when building
	from source while an older version of qpdf is installed. Fixes #158.

	* Add support for TIFF predictor for LZW and Flate streams. Now
	all predictor functions are supported. Fixes #171.

2017-12-25  Jay Berkenbilt  <ejb@ql.org>

	* Clarify documentation around options that control parsing but
	not output creation. Two options: --suppress-recovery and
	--ignore-xref-streams, were documented in the "Advanced
	Transformation Options" section of the manual and --help output
	even though they are not related to output. These are now
	described in a separate section called "Advanced Parsing Options."

	* Implement remaining PNG filters for decode. Prior versions could
	decode only the "up" filter. Now all PNG filters (sub, up,
	average, Paeth, optimal) are supported for decoding. Thanks to
	Tobias Hoffmann for providing a test PDF file that has images with
	all PNG filters along with different numbers of bits per sample
	and samples per pixel, and thanks to Casey Rojas for providing
	implementations of the remaining PNG filters.

	The implementation of the remaining PNG filters changed the
	interface to the private Pl_PNGFilter class, but this class's
	header file is not in the installation, and there is no public
	interface to the class. Within the library, the class is never
	allocated on the stack; it is only ever dynamically allocated. As
	such, this does not actually break binary compatibility of the
	library.