remove obsolete Mac OS build instructions

INSTALL.rst

@@ -195,72 +195,6 @@ By default the package will be installed under ``/usr/local``.  Run ``python3
 setup.py --help install`` for installation options.
 
 
-Mac OS X: MacPorts
-==================
-
-The following instructions are valid for Kwant 1.1 with Python 2.7.  They need
-to be updated for Kwant 1.2.  (Help is welcome.)
-
-The required dependencies of Kwant are best installed with one of the packaging
-systems. Here we only consider the case of `MacPorts
-<https://www.macports.org>`_ in detail. Some remarks for homebrew are given
-below.
-
-1. Install a recent version of MacPorts, as explained in the `installation
-   instructions of MacPorts <https://www.macports.org/install.php>`_.
-
-2. Install the required dependencies::
-
-       sudo port install gcc47 python27 py27-numpy py27-scipy py27-matplotlib mumps_seq
-       sudo port select --set python python27
-
-3. Unpack Tinyarray, enter its directory, build and install::
-
-       python setup.py build
-       sudo python setup.py install
-
-4. Unpack Kwant, go to the Kwant directory, and edit ``build.conf`` to read::
-
-       [mumps]
-       include_dirs = /opt/local/include
-       library_dirs = /opt/local/lib
-       libraries = zmumps_seq mumps_common_seq pord_seq esmumps scotch scotcherr mpiseq gfortran
-
-5. Then, build and install Kwant. ::
-
-       CC=gcc-mp-4.7 LDSHARED='gcc-mp-4.7 -shared -undefined dynamic_lookup' python setup.py build
-       sudo python setup.py install
-
-You might note that installing Kwant on Mac OS X is somewhat more involved than
-installing on Linux. Part of the reason is that we need to mix Fortran and C
-code in Kwant: While C code is usually compiled using Apple compilers,
-Fortran code must be compiled with the Gnu Fortran compiler (there is
-no Apple Fortran compiler). For this reason we force the Gnu compiler suite
-with the environment variables ``CC`` and ``LDSHARED`` as shown above.
-
-
-Mac OS X: homebrew
-==================
-
-The following instructions are valid for Kwant 1.1 with Python 2.7.  They need
-to be updated for Kwant 1.2.  (Help is welcome.)
-
-It is also possible to build Kwant using homebrew. The dependencies can be
-installed as ::
-
-    brew install gcc python
-    brew tap homebrew/science
-    brew tap homebrew/python
-    brew tap kwant-project/kwant
-    pip install pytest pytest-runner six
-    brew install numpy scipy matplotlib
-
-Note that during the installation you will be told which paths to add when you
-want to compile/link against scotch/metis/mumps; you need to add these to the
-build.conf file. Also, when linking against MUMPS, one needs also to link
-against METIS (in addition to the libraries needed for MacPorts).
-
-
 Microsoft Windows
 =================