gnu: Add emacs-let-alist. * gnu/packages/emacs.scm (let-alist): New variable.
emacs: Add "View graph" action to graph popup. * emacs/guix-command.el: Require 'guix-external'. (guix-run-view-graph): New function. (guix-command-additional-execute-arguments, guix-command-special-executors): Add entries for "View graph" action.
emacs: Allow users to choose a 'find-file' function. * emacs/guix-utils.el (guix-find-file-function): New variable. (guix-find-file): Use it.
emacs: Add code to run 'dot' program. * emacs/guix-external.el: New file. * emacs.am (ELFILES): Add it.
emacs: Add code to pipe guix output to external program. * emacs/guix-main.scm: Use (ice-9 popen) module. (pipe-guix-output): New procedure.
gnu: Add Guile-Present. * gnu/packages/gtk.scm (guile-present): New variable.
gnu: Add Guile-RSVG. * gnu/packages/gtk.scm (guile-rsvg): New variable. * gnu/packages/patches/guile-rsvg-pkgconfig.patch: New file. * gnu-system.am (dist_patch_DATA): Add it.
gnu: Add frescobaldi. * gnu/packages/music.scm (frescobaldi): New variable.
gnu: Add python-ly. * gnu/packages/python.scm (python-ly): New variable.
gnu: Add python-poppler-qt4. * gnu/packages/pdf.scm (python-poppler-qt4): New variable.
gnu: Add poppler-qt4. * gnu/packages/pdf.scm (poppler-qt4): New variable.
gnu: Add ruby-thor. * gnu/packages/ruby.scm (ruby-thor): New variable.
gnu: Add ruby-xml-simple. * gnu/packages/ruby.scm (ruby-xml-simple): New variable.
gnu: Add ruby-orderedhash. * gnu/packages/ruby.scm (ruby-orderedhash): New variable.
gnu: Add ruby-atoulme-antwrap. * gnu/packages/ruby.scm (ruby-atoulme-antwrap): New variable.
gnu: Add ruby-rjb. * gnu/packages/ruby.scm (ruby-rjb): New variable.
gnu: Add ruby-builder. * gnu/packages/ruby.scm (ruby-builder): New variable.
gnu: libedit: Enable wide character support. * gnu/packages/libedit.scm (libedit)[arguments]: Add "--enable-widec" to configure flags.
gnu: libedit: Update to 20150325-3.1. * gnu/packages/libedit.scm (libedit): Update to 20150325-3.1.
build: Add R build system. * guix/build-system/r.scm: New file. * guix/build/r-build-system: New file. * Makefile.am (MODULES): Add new files. * doc/guix.texi (Build Systems): Document r-build-system.