gnu: Fix ambiguous 'zip' reference.

* gnu/packages/photo.scm: Hide 'zip' from (srfi srfi-1).

ui: Non-zero exit for compound '&message' and '&error-location' conditions.

* guix/ui.scm (call-with-error-handling): When both 'message?' and
'error-location?' are true, add call to 'exit'.

system: examples: Add a template for BeagleBone Black.

* gnu/system/examples/beaglebone-black.tmpl: New file.
* Makefile.am (EXAMPLES): Add it.
* gnu/system/install.scm (/etc/configuration-files): Add it.

gnu: claws-mail: Update to 3.16.0.

* gnu/packages/mail.scm (claws-mail): Update to 3.16.0.

services: nginx: Allow to add raw content to the server blocks.

* doc/guix.texi (Web Services): Document 'raw-content'.
* gnu/services/web.scm (<nginx-server-configuration>)[raw-content]: New field.
(emit-nginx-server-config): Add it.

services: nginx: Replace 'http-port' and 'https-port' with 'listen'.

* doc/guix.texi (Web Services, Version Control Services): Update accordingly.
* gnu/services/certbot.scm (certbot-nginx-server-configurations): Likewise.
* gnu/services/version-control.scm (%cgit-configuration-nginx): Likewise.
* gnu/services/web.scm (<nginx-server-configuration>,
emit-nginx-server-config): Likewise.
* gnu/tests/version-control.scm (%cgit-configuration-nginx,
%git-nginx-configuration): Likewise.
* gnu/tests/web.scm (%nginx-servers, %php-fpm-nginx-server-blocks): Likewise.

gnu: r-seurat: Update to 2.1.0.

* gnu/packages/bioinformatics.scm (r-seurat): Update to 2.1.0.
[propagated-inputs]: Add r-diffusionmap, r-dtw, r-ggjoy, r-hmisc, r-ica,
r-mass, r-matrix, r-nmf, r-plotly, r-sdmtools, r-tidyr; remove r-plyr,
r-rcppeigen, r-fastica.

gnu: Add r-diffusionmap.

* gnu/packages/graph.scm (r-diffusionmap): New variable.

gnu: Add r-ggjoy.

* gnu/packages/cran.scm (r-ggjoy): New variable.

gnu: Add r-ggridges.

* gnu/packages/cran.scm (r-ggridges): New variable.

gnu: Add r-scatterplot3d.

* gnu/packages/cran.scm (r-scatterplot3d): New variable.

gnu: Add r-sdmtools.

* gnu/packages/cran.scm (r-sdmtools): New variable.

gnu: Add r-dtw.

* gnu/packages/cran.scm (r-dtw): New variable.

gnu: Add r-ica.

* gnu/packages/cran.scm (r-ica): New variable.

gnu: r-seurat: Fix ModularityOptimizer.jar.

* gnu/packages/bioinformatics.scm (r-seurat)[arguments]: Include Main-Class
attribute in manifest.

gnu: qmidiarp: Update to 0.6.5.

* gnu/packages/music.scm (qmidiarp): Update to 0.6.5.

gnu: Add noise-repellent.

* gnu/packages/audio.scm (noise-repellent): New variable.

gnu: Add aj-snapshot.

* gnu/packages/music.scm (aj-snapshot): New variable.

gnu: Add jack-capture.

* gnu/packages/music.scm (jack-capture): New variable.

gnu: Add qjackrcd.

* gnu/packages/audio.scm (qjackrcd): New variable.