gnu: Add GenomicFeatures.

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

gnu: Add rtracklayer.

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

gnu: Add GenomicAlignments.

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

gnu: Add SummarizedExperiment.

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

gnu: Add Rsamtools.

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

gnu: Add Biostrings.

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

gnu: Add BiocParallel.

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

gnu: Add biomaRt.

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

gnu: Add AnnotationDbi.

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

gnu: Add Biobase.

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

gnu: Add snow.

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

gnu: Add futile.logger.

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

gnu: Add futile.options.

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

gnu: Add lambda.r.

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

gnu: Add r-xml.

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

gnu: Add RCurl.

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

gnu: Add RSQLite.

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

import: Rename "cran-fetch" to "fetch-description".

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

import: Add package->upstream-name procedure.

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

gnu: Add xmlstarlet.

* gnu/packages/xml.scm (xmlstarlet): New variable.