Add guix.scm for installation from source

In the MMTK directory, do one of
  - guix build -f guix.scm
  - guix package -i -f guix.scm

guix.scm

@@ -0,0 +1,40 @@
+(use-modules (guix)
+             (guix build-system python)
+             ((guix licenses) #:prefix license:)
+             (guix git-download)
+             (gnu packages python)
+             (gnu packages python-xyz)
+             (gnu packages maths))
+
+(package
+  (name "python2-mmtk")
+  (version "2.7.12")
+  (source (local-file (dirname (current-filename))
+                      #:recursive? #t))
+  (build-system python-build-system)
+  (native-inputs
+   `(("netcdf" ,netcdf)))
+  (propagated-inputs
+   `(("python-scientific" ,python2-scientific)
+     ("python-tkinter" ,python-2 "tk")))
+  (arguments
+   `(#:python ,python-2
+     #:tests? #f
+     #:phases
+     (modify-phases %standard-phases
+       (add-before 'build 'includes-from-scientific
+         (lambda* (#:key inputs #:allow-other-keys)
+           (mkdir-p "Include/Scientific")
+           (copy-recursively
+            (string-append
+             (assoc-ref inputs "python-scientific")
+             "/include/python2.7/Scientific")
+            "Include/Scientific"))))))
+  (home-page "http://dirac.cnrs-orleans.fr/MMTK")
+  (synopsis "Python library for molecular simulation")
+  (description "MMTK is a library for molecular simulations with an emphasis
+on biomolecules.  It provides widely used methods such as Molecular Dynamics
+and normal mode analysis, but also basic routines for implementing new methods
+for simulation and analysis.  The library is currently not actively maintained
+and works only with Python 2 and NumPy < 1.9.")
+  (license license:cecill-c))