gnu: khmer: Add aarch64-linux to supported systems.

* gnu/packages/bioinformatics.scm (khmer)[supported-systems]: Add
aarch64-linux to the supported systems.

gnu: nss-certs: Update to 3.35.

* gnu/packages/certs.scm (nss-certs): Update to 3.35.

gnu: iq80-snappy: Improve synopsis & description.

* gnu/packages/compression.scm (iq80-snappy)[synopsis, description]: Fix
typos and add ‘(de)compressor’ keywords.

gnu: go: Improve description.

* gnu/packages/golang.scm (go-1.4)[description]: Edit for clarity.

gnu: go@1.9: Drop left-over work-around.

* gnu/packages/golang.scm (go-1.9)[arguments]: Remove substitution for
fixed bug from the ‘prebuild’ phase.

gnu: direnv: Edit description.

* gnu/packages/shellutils.scm (direnv)[description]: Edit and use @file.

gnu: direnv: Use HTTPS for home page.

* gnu/packages/shellutils.scm (direnv)[home-page]: Use HTTPS.

gnu: youtube-dl: Return #t from phases.

* gnu/packages/video.scm (youtube-dl)[arguments]: Return #t from
‘fix-the-data-directories’ phase.

gnu: youtube-dl: Update to 2018.01.21.

* gnu/packages/video.scm (youtube-dl): Update to 2018.01.21.
[description]: Update.  ‘A few’ is simply no longer true.

gnu: mktorrent: Add missing @dfn to description.

* gnu/packages/bittorrent.scm (mktorrent)[description]: Add missing @dfn.

gnu: libtorrent-rasterbar: Update home page.

* gnu/packages/bittorrent.scm (libtorrent-rasterbar)[home-page]: Use extant domain.

gnu: newt: Update to 0.52.20.

* gnu/packages/slang.scm (newt): Update to 0.52.20.

gnu: mia: Update to 2.4.6.

* gnu/packages/image-processing.scm (mia): Update to 2.4.6.

gnu: Add python2-graphite-web.

* gnu/packages/monitoring.scm (python2-graphite-web): New variable.

gnu: Add python2-carbon.

* gnu/packages/monitoring.scm (python2-carbon): New variable.

gnu: Add python-whisper.

* gnu/packages/monitoring.scm (python-whisper, python2-whisper): New
variables.

gnu: Add python-django-tagging.

* gnu/packages/django.scm (python-django-tagging, python2-django-tagging): New
variables.

gnu: Add python-txamqp.

* gnu/packages/python.scm (python-txamqp, python2-txamqp): New variables.

gnu: emacs-tiny: Fix indentation.

* gnu/packages/emacs.scm (emacs-tiny): Fix indentation.

gnu: emacs-request: Update to 0.3.0.

* gnu/packages/emacs.scm (emacs-request): Update to 0.3.0.
[source]: Fetch with git.