* doc/guix.texi (Invoking guix package): Add elaborate --search example
using recsel and sexes.

* gnu/packages/textutils.scm (pfff): New variable.

This is a heavy-weight and uncommon feature.  See
<http://lists.gnu.org/archive/html/guix-devel/2015-12/msg00701.html>.

* gnu/packages/video.scm (mpv)[inputs]: Remove 'samba'.

* emacs/guix-main.scm (%package-param-alist): Add 'systems'.
* emacs/guix-ui-package.el (guix-package-info-insert-systems): New
  procedure.
  (guix-package-info-format): Add it.
  (guix-output-info-format): Likewise.
  (guix-package-info-titles): Add "Supported systems" title.

* gnu/packages/bioinformatics.scm (r-genomation): New variable.

* gnu/packages/bioinformatics.scm (r-seqpattern): New variable.

* gnu/packages/bioinformatics.scm (r-impute): New variable.

* gnu/packages/bioinformatics.scm (r-bsgenome): New variable.

* gnu/packages/statistics.scm (r-plotly): New variable.

* gnu/packages/statistics.scm (r-viridis): New variable.

* gnu/packages/bioinformatics.scm (r-topgo): New variable.

* gnu/packages/statistics.scm (r-matrixstats): New variable.

* gnu/packages/statistics.scm (r-r-rsp): New variable.

* gnu/packages/statistics.scm (r-r-cache): New variable.

* gnu/packages/statistics.scm (r-r-utils): New variable.

* gnu/packages/statistics.scm (r-r-oo): New variable.

* gnu/packages/statistics.scm (r-r-methodss3): New variable.

* gnu/packages/statistics.scm (r-base64enc): New variable.

* gnu/packages/statistics.scm (r-dt): New variable.

* gnu/packages/statistics.scm (r-sparsem): New variable.

* gnu/packages/bioinformatics.scm (r-go-db): New variable.

* gnu/packages/bioinformatics.scm (r-genomicfeatures): New variable.

* gnu/packages/bioinformatics.scm (r-rtracklayer): New variable.

* gnu/packages/bioinformatics.scm (r-genomicalignments): New variable.

* gnu/packages/bioinformatics.scm (r-summarizedexperiment): New variable.

* gnu/packages/bioinformatics.scm (r-rsamtools): New variable.

* gnu/packages/bioinformatics.scm (r-biostrings): New variable.

* gnu/packages/bioinformatics.scm (r-biocparallel): New variable.

* gnu/packages/bioinformatics.scm (r-biomart): New variable.

* gnu/packages/bioinformatics.scm (r-annotationdbi): New variable.

* gnu/packages/bioinformatics.scm (r-biobase): New variable.

* gnu/packages/statistics.scm (r-snow): New variable.

* gnu/packages/statistics.scm (r-futile-logger): New variable.

* gnu/packages/statistics.scm (r-futile-options): New variable.

* gnu/packages/statistics.scm (r-lambda-r): New variable.

* gnu/packages/statistics.scm (r-xml): New variable.

* gnu/packages/statistics.scm (r-rcurl): New variable.

* gnu/packages/statistics.scm (r-rsqlite): New variable.

* guix/import/cran.scm (cran-fetch): Rename procedure ...
(fetch-description): ... to this.

* guix/import/cran.scm (package->upstream-name): New procedure.