gnu: Add perl-cwd-guard.

* gnu/packages/perl.scm (perl-cwd-guard): New variable.

gnu: Add perl-devel-checkcompiler.

* gnu/packages/perl.scm (perl-devel-checkcompiler): New variable.

gnu: Add perl-ev.

* gnu/packages/libevent.scm (perl-ev): New variable.

gnu: Add perl-canary-stability.

* gnu/packages/perl.scm (perl-canary-stability): New variable.

gnu: Add perl-async-interrupt.

* gnu/packages/perl.scm (perl-async-interrupt): New variable.

gnu: leveldb: Update to 1.20.

* gnu/packages/databases.scm (leveldb): Update to 1.20.

gnu: Add jacal.

* gnu/packages/maths.scm (jacal): New variable.
* gnu/packages/patches/jacal-fix-texinfo.patch: New file.

gnu: Add scm.

* gnu/packages/scheme.scm (scm): New variable.

gnu: Add slib.

* gnu/packages/scheme.scm (slib): New variable.

gnu: Merge the two stellaria into one.

* gnu/packages/astronomy.scm (stellaruim): Merge details from stellarium-0.14.
* gnu/packages/education.scm (stellarium): Remove variable.

gnu: bundler: Update to 1.14.5.

* gnu/packages/ruby.scm (bundler): Update to 1.14.5.

gnu: diamond: Update to 0.8.36.

* gnu/packages/bioinformatics.scm (diamond): Update to 0.8.36.

gnu: mutt: Update to 1.8.0.

* gnu/packages/mail.scm (mutt): Update to 1.8.0.

gnu: nano: Update to 2.7.5.

* gnu/packages/nano.scm (nano): Update to 2.7.5.
[description]: Updated with help from 'guix lint'.

services: ssh: Remove 'openssh-service' exported symbol.

This is a followup to commit d8f3128119d32bcc186c8a1fe15b037bba25b4b8.
Reported by thomasd on #guix.

* gnu/services/ssh.scm: Do not export 'openssh-service' as it does not
exist.

gnu: Add stellarium.

* gnu/packages/astronomy.scm (stellarium): New variable.

gnu: cbatticon: Update to 1.6.5.

* gnu/packages/admin.scm (cbatticon): Update to 1.6.5.

gnu: di: Update to 4.43.

* gnu/packages/admin.scm (di): Update to 4.43.

gnu: tidy-html: Update to 5.4.0.

* gnu/packages/web.scm (tidy-html): Update to 5.4.0.

gnu: txt2man: Update to 1.6.0.

* gnu/packages/man.scm (txt2man): Update to 1.6.0.