gnu: Add cursynth

* gnu/packages/cursynth.scm: New file
* gnu-system.am (GNU_SYSTEM_MODULES): Add it

gnu: autotools: Add Autoconf 2.68; turn 'autoconf-wrapper' into a procedure.

* gnu/packages/autotools.scm (autoconf-2.68): New variable.
  (autoconf-wrapper): Turn into a procedure.  Turn comment into a
  docstring.
  (automake): Adjust accordingly.

Co-authored-by: Ludovic Courtès <ludo@gnu.org>

gnu: tor: Upgrade to 0.2.4.21.

* gnu/packages/tor.scm (tor): Upgrade to 0.2.4.21.

gnu: Provide single-precision fftw library for pulseaudio

* gnu/packages/algebra.scm (fftwf): New variable
* gnu/packages/pulseaudio.scm (pulseaudio): Use it

gnu: cmake: Install man pages and docs in share/{man,doc}.

* gnu/packages/cmake.scm (cmake): Pass --mandir and --docdir to configure.
  Rewrite the code that selects the first two components of the version.

gnu: flac: Install man pages in share/man.

* gnu/packages/xiph.scm (flac): Add --mandir configure flag.

gnu: libvorbis: disable parallel tests

* gnu/packages/xiph.scm (libvorbis): disable parallel tests

gnu: openssh: Upgrade to 6.6p1.

* gnu/packages/ssh.scm (openssh): Upgrade to 6.6p1.

gnu: tzdata: Upgrade to 2014a.

gnu: lynx: Upgrade to 2.8.8rel.2.

* gnu/packages/lynx.scm (lynx): Upgrade to 2.8.8rel.2.

gnu: bc: Install docs in share/man and share/info.

* gnu/packages/algebra.scm (bc): Pass --mandir and --infodir to configure.

gnu: unzip: Install man pages in share/man.

* gnu/packages/zip.scm (unzip): Substitute /share/man/ for /man/ in Makefile.

gnu: screen: Install docs in share/man and share/info.

* gnu/packages/screen.scm (screen): Add --mandir and --infodir
  configure flags.

gnu: netcat: Install docs in share/man and share/info.

* gnu/packages/admin.scm (netcat): Add --mandir and --infodir
  configure flags.

gnu: xterm: Upgrade to 303.

* gnu/packages/xorg.scm (xterm): Upgrade to 303.

gnu: imagemagick: Upgrade to 6.8.8-8.

* gnu/packages/imagemagick.scm (imagemagick): Upgrade to 6.8.8-8.

gnu: Add Window Maker.

* gnu/packages/gnustep.scm: New file.
* gnu-system.am (GNU_SYSTEM_MODULES): Add it.

gnu: libxft: Propagate Freetype and Fontconfig.

* gnu/packages/xorg.scm (libxft): Move Freetype and Fontconfig from
  'inputs' to 'propagated-inputs'.

gnu: luajit: Update to 2.0.3.

* gnu/packages/lua.scm (luajit): Update to 2.0.3.

gnu: python: Change URL to https.

* gnu/packages/python.scm (python-2, python)[source]: Change URL to
  https.  This makes sure GnuTLS is available in the derivation that
  downloads the source, which is required since http URLs get redirected
  to https anyway.  Reported by Manolis Ragkousis <manolis837@gmail.com>.