Update lxml to 4.4.0

[pyup-bot]

This PR updates lxml from 4.2.1 to 4.4.0.

Changelog

4.4.0

==================

Features added
--------------

* ``Element.clear()`` accepts a new keyword argument ``keep_tail=True`` to
clear everything but the tail text.  This is helpful in some document-style
use cases.

* When creating attributes or namespaces from a dict in Python 3.6+, lxml now
preserves the original insertion order of that dict, instead of always sorting
the items by name.  A similar change was made for ElementTree in CPython 3.8.
See https://bugs.python.org/issue34160

* Integer elements in ``lxml.objectify`` implement the ``__index__()`` special method.

* GH269: Read-only elements in XSLT were missing the ``nsmap`` property.
Original patch by Jan Pazdziora.

* ElementInclude can now restrict the maximum inclusion depth via a ``max_depth``
argument to prevent content explosion.  It is limited to 6 by default.

* The ``target`` object of the XMLParser can have ``start_ns()`` and ``end_ns()``
callback methods to listen to namespace declarations.

* The ``TreeBuilder`` has new arguments ``comment_factory`` and ``pi_factory`` to
pass factories for creating comments and processing instructions, as well as
flag arguments ``insert_comments`` and ``insert_pis`` to discard them from the
tree when set to false.

* A `C14N 2.0 <https://www.w3.org/TR/xml-c14n2/>`_ implementation was added as
``etree.canonicalize()``, a corresponding ``C14NWriterTarget`` class, and
a ``c14n2`` serialisation method.

Bugs fixed
----------

* When writing to file paths that contain the URL escape character '%', the file
path could wrongly be mangled by URL unescaping and thus write to a different
file or directory.  Code that writes to file paths that are provided by untrusted
sources, but that must work with previous versions of lxml, should best either
reject paths that contain '%' characters, or otherwise make sure that the path
does not contain maliciously injected '%XX' URL hex escapes for paths like '../'.

* Assigning to Element child slices with negative step could insert the slice at
the wrong position, starting too far on the left.

* Assigning to Element child slices with overly large step size could take very
long, regardless of the length of the actual slice.

* Assigning to Element child slices of the wrong size could sometimes fail to
raise a ValueError (like a list assignment would) and instead assign outside
of the original slice bounds or leave parts of it unreplaced.

* The ``comment`` and ``pi`` events in ``iterwalk()`` were never triggered, and
instead, comments and processing instructions in the tree were reported as
``start`` elements.  Also, when walking an ElementTree (as opposed to its root
element), comments and PIs outside of the root element are now reported.

* LP1827833: The RelaxNG compact syntax support was broken with recent versions
of ``rnc2rng``.

* LP1758553: The HTML elements ``source`` and ``track`` were added to the list
of empty tags in ``lxml.html.defs``.

* Registering a prefix other than "xml" for the XML namespace is now rejected.

* Failing to write XSLT output to a file could raise a misleading exception.
It now raises ``IOError``.

Other changes
-------------

* Support for Python 3.4 was removed.

* When using ``Element.find*()`` with prefix-namespace mappings, the empty string
is now accepted to define a default namespace, in addition to the previously
supported ``None`` prefix.  Empty strings are more convenient since they keep
all prefix keys in a namespace dict strings, which simplifies sorting etc.

* The ``ElementTree.write_c14n()`` method has been deprecated in favour of the
long preferred ``ElementTree.write(f, method="c14n")``.  It will be removed
in a future release.

4.3.5

==================

* Rebuilt with Cython 0.29.13 to support Python 3.8.

4.3.4

==================

* Rebuilt with Cython 0.29.10 to support Python 3.8.

4.3.3

==================

Bugs fixed
----------

* Fix leak of output buffer and unclosed files in ``_XSLTResultTree.write_output()``.

4.3.2

==================

Bugs fixed
----------

* Crash in 4.3.1 when appending a child subtree with certain text nodes.

Other changes
-------------

* Built with Cython 0.29.6.

4.3.1

==================

Bugs fixed
----------

* LP1814522: Crash when appending a child subtree that contains unsubstituted
entity references.

Other changes
-------------

* Built with Cython 0.29.5.

4.3.0

==================

Features added
--------------

* The module ``lxml.sax`` is compiled using Cython in order to speed it up.

* GH267: ``lxml.sax.ElementTreeProducer`` now preserves the namespace prefixes.
If two prefixes point to the same URI, the first prefix in alphabetical order
is used.  Patch by Lennart Regebro.

* Updated ISO-Schematron implementation to 2013 version (now MIT licensed)
and the corresponding schema to the 2016 version (with optional "properties").

Other changes
-------------

* GH270, GH271: Support for Python 2.6 and 3.3 was removed.
Patch by hugovk.

* The minimum dependency versions were raised to libxml2 2.9.2 and libxslt 1.1.27,
which were released in 2014 and 2012 respectively.

* Built with Cython 0.29.2.

4.2.6

==================

Bugs fixed
----------

* LP1799755: Fix a DeprecationWarning in Py3.7+.

* Import warnings in Python 3.6+ were resolved.

4.2.5

==================

Bugs fixed
----------

* Javascript URLs that used URL escaping were not removed by the HTML cleaner.
Security problem found by Omar Eissa.  (CVE-2018-19787)

4.2.4

==================

Features added
--------------

* GH259: Allow using ``pkg-config`` for build configuration.
Patch by Patrick Griffis.

Bugs fixed
----------

* LP1773749, GH268: Crash when moving an element to another document with
``Element.insert()``.
Patch by Alexander Weggerle.

4.2.3

==================

Bugs fixed
----------

* Reverted GH265: lxml links against zlib as a shared library again.

4.2.2

==================

Bugs fixed
----------

* GH266: Fix sporadic crash during GC when parse-time schema validation is used
and the parser participates in a reference cycle.
Original patch by Julien Greard.

* GH265: lxml no longer links against zlib as a shared library, only on static builds.
Patch by Nehal J Wani.

Links

• PyPI: https://pypi.org/project/lxml
• Changelog: https://pyup.io/changelogs/lxml/
• Homepage: http://lxml.de/