Cutadapt

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* Fix 110: Counts for 'too short' and 'too long' reads were swapped in statistics.
* Fix 115: Make ``--trim-n`` work also on second read for paired-end data.

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* Support single-pass paired-end trimming with the new ``-A``/``-G``/``-B``/``-U``
parameters. These work just like their -a/-g/-b/-u counterparts, but they
specify sequences that are removed from the *second read* in a pair.

Also, if you start using one of those options, the read modification options
such as ``-q`` (quality trimming) are applied to *both* reads. For backwards
compatibility, read modifications are applied to the first read only if
neither of ``-A``/``-G``/``-B``/``-U`` is used. See `the
documentation <http://cutadapt.readthedocs.io/en/latest/guide.html#paired-end>`_
for details.

This feature has not been extensively tested, so please give feedback if
something does not work.
* The report output has been re-worked in order to accomodate the new paired-end
trimming mode. This also changes the way the report looks like in single-end
mode. It is hopefully now more accessible.
* Chris Mitchell contributed a patch adding two new options: ``--trim-n``
removes any ``N`` bases from the read ends, and the ``--max-n`` option can be
used to filter out reads with too many ``N``.
* Support notation for repeated bases in the adapter sequence: Write ``A{10}``
instead of ``AAAAAAAAAA``. Useful for poly-A trimming: Use ``-a A{100}`` to
get the longest possible tail.
* Quality trimming at the 5' end of reads is now supported. Use ``-q 15,10`` to
trim the 5' end with a cutoff of 15 and the 3' end with a cutoff of 10.
* Fix incorrectly reported statistics (> 100% trimmed bases) when ``--times``
set to a value greater than one.
* Support .xz-compressed files (if running in Python 3.3 or later).
* Started to use the GitHub issue tracker instead of Google Code. All old issues
have been moved.

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* IUPAC characters are now supported. For example, use ``-a YACGT`` for an
adapter that matches both ``CACGT`` and ``TACGT`` with zero errors. Disable
with ``-N``. By default, IUPAC characters in the read are not interpreted in
order to avoid matches in reads that consist of many (low-quality) ``N``
bases. Use ``--match-read-wildcards`` to enable them also in the read.
* Support for demultiplexing was added. This means that reads can be written to
different files depending on which adapter was found. See `the section in the
documentation <http://cutadapt.readthedocs.org/en/latest/guide.html#demultiplexing>`_
for how to use it. This is currently only supported for single-end reads.
* Add support for anchored 3' adapters. Append ``$`` to the adapter sequence to
force the adapter to appear in the end of the read (as a suffix). Closes
issue 81.
* Option ``--cut`` (``-u``) can now be specified twice, once for each end of the
read. Thanks to Rasmus Borup Hansen for the patch!
* Options ``--minimum-length``/``--maximum-length`` (``-m``/``-M``) can be used
standalone. That is, cutadapt can be used to filter reads by length without
trimming adapters.
* Fix bug: Adapters read from a FASTA file can now be anchored.

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* Fix bug: Ensure ``--format=...`` can be used even with paired-end input.
* Fix bug: Sometimes output files would be incomplete because they were not
closed correctly.
* Alignment algorithm is a tiny bit faster.
* Extensive work on the documentation. It's now available at
https://cutadapt.readthedocs.org/ .
* For 3' adapters, statistics about the bases preceding the trimmed adapter
are collected and printed. If one of the bases is overrepresented, a warning
is shown since this points to an incomplete adapter sequence. This happens,
for example, when a TruSeq adapter is used but the A overhang is not taken
into account when running cutadapt.
* Due to code cleanup, there is a change in behavior: If you use
``--discard-trimmed`` or ``--discard-untrimmed`` in combination with
``--too-short-output`` or ``--too-long-output``, then cutadapt now writes also
the discarded reads to the output files given by the ``--too-short`` or
``--too-long`` options. If anyone complains, I will consider reverting this.
* Galaxy support files are now in `a separate
repository <https://bitbucket.org/lance_parsons/cutadapt_galaxy_wrapper>`_.

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* Adapter sequences can now be read from a FASTA file. For example, write
``-a file:adapters.fasta`` to read 3' adapters from ``adapters.fasta``. This works
also for ``-b`` and ``-g``.
* Add the option ``--mask-adapter``, which can be used to not remove adapters,
but to instead mask them with ``N`` characters. Thanks to Vittorio Zamboni
for contributing this feature!
* U characters in the adapter sequence are automatically converted to T.
* Do not run Cython at installation time unless the --cython option is provided.
* Add the option -u/--cut, which can be used to unconditionally remove a number
of bases from the beginning or end of each read.
* Make ``--zero-cap`` the default for colorspace reads.
* When the new option ``--quiet`` is used, no report is printed after all reads
have been processed.
* When processing paired-end reads, cutadapt now checks whether the reads are
properly paired.
* To properly handle paired-end reads, an option --untrimmed-paired-output was
added.