gnu: znc: Update source URL.

* gnu/packages/messaging.scm (znc)[source]: Update URL.

gnu: libpng: Update to 1.5.26 [fixes CVE-2015-8472 and CVE-2015-8540].

* gnu/packages/image.scm (libpng): Update to 1.5.26.

gnu: gdk-pixbuf: Update to 2.32.3. (fixes CVE-2015-4491)

* gnu/packages/gtk.scm (gdk-pixbuf): Update to 2.32.3.

gnu: cups-filters: Update to 1.4.0. (fixes CVE-2015-8560)

* gnu/packages/cups.scm (cups-filters): Update to 1.4.0.

gnu: xlockmore: Update to 5.46.

* gnu/packages/xdisorg.scm (xlockmore): Update to 5.46.

gnu: xlockmore: Add alternate URL.

* gnu/packages/xdisorg.scm (xlockmore)[source]: Add alternate URL.

gnu: wmctrl: Update source URL.

* gnu/packages/xdisorg.scm (wmctrl)[source]: Update URL.

gnu: colordiff: Update to 1.0.16.

* gnu/packages/patchutils.scm (colordiff): Update to 1.0.16.

gnu: colordiff: Update source URL.

* gnu/packages/patchutils.scm (colordiff)[source]: Update URL.

gnu: opus-tools: Update source URL.

* gnu/packages/xiph.sch (opus-tools)[source]: Update URL.

gnu: moreutils: Update to 0.57.

* gnu/packages/moreutils.scm (moreutils): Update to 0.57.

gnu: lynx: Update source URL.

* gnu/packages/lynx.scm (lynx)[source]: Update URL.

gnu: libsodium: Add alternate URL.

* gnu/packages/crypto.scm (libsodium)[source]: Add alternate URL.

gnu: libev: Update source URL.

* gnu/packages/libevent.scm (libev)[source]: Update URL.

gnu: hevea: Update URL.

* gnu/packages/ocaml.scm (hevea)[source]: Update URL.

gnu: exim: Update to 4.86.

* gnu/packages/mail.scm (exim): Update to 4.86.

gnu: exim: Add alternate URL.

* gnu/packages/mail.scm (exim)[source]: Add alternate URL.

gnu: eudev: Update home-page URL.

* gnu/packages/linux.scm (eudev)[home-page]: Add up-to-date URL.

guix package: Fix typo in comment.

* guix/scripts/package.scm: Fix typo.

gnu: Add Bristol.

* gnu/packages/music.scm (bristol): New variable.