Update getting_started docs

docs/source/getting_started.rst

@@ -13,14 +13,17 @@ Requirements
 
 * `python >= 3.x <https://www.python.org/>`_
 
-  * `numpy >= 1.13.x <http://www.numpy.org/>`_
+  * `numpy <http://www.numpy.org/>`_
   * `scipy <https://www.scipy.org/>`_
   * `cython <http://cython.org/>`_
   * `h5py <http://www.h5py.org/>`_
+  * `matplotlib <http://www.matplotlib.org/>`_
+  * `psutil <https://pypi.org/project/psutil/>`_
+  * `joblib <https://joblib.readthedocs.io/>`_
+  * `six <https://six.readthedocs.io/>`_
+  * `astropy <https://www.astropy.org/>`_
   * `yt >= 3.3 <https://bitbucket.org/yt_analysis/yt>`_
 
-    * `sympy <http://www.sympy.org/en/index.html>`_
-
 ----
 
 Installation
@@ -30,68 +33,86 @@ Python and friends
 ------------------
 
 Since this is a python package, you must have python installed!
-``CAESAR`` should be py2 and py3 compatible so feel free to pick
-whichever you are most comforatable with.  This said, the developers
-do not support issues related to py2 anymore.
-
-If you do not have a pre-existing python installation (other than your
-system's native python, of which we do **not** recommend using) we
-*strongly* encourage you to consider a pre-packaged distribution such
-as `Anaconda <https://www.continuum.io/downloads>`_.  Anaconda for
-instance, will install an isolated python environment in your home
+``CAESAR`` formally requires python-3.  Some basic functionality is
+still compatible with python-2, but we have discontinued further
+support for this in ``CAESAR``.
+
+We strongly encourage using a pre-packaged python distribution,
+such as `Anaconda <https://www.anaconda.com/products/individual>`_.
+This will install an isolated python environment in your home
 directory giving you full access to install and change packages
 without fear of screwing up your system's default python install.
-Another advantage is that it comes with nearly everything you need to
-get started working with python (numpy/scipy/matplotlib/etc).
+Another advantage is that it comes with nearly everything you need
+to get started working with python (numpy/scipy/matplotlib/etc).
 
-A more
-minimalist option is `Miniconda
-<http://conda.pydata.org/miniconda.html>`_.  This package gives you
-the functionality of Anaconda without all of the default packages.
+----
 
 
-Anaconda / Miniconda
-^^^^^^^^^^^^^^^^^^^^
+Dependencies
+------------
 
-Regardless of if you use Anaconda or Miniconda, all dependencies can
-easily be installed via the ``conda`` command:
+Installing the main dependencies is very easy under Anaconda, or using the
+python package manager `pip <https://pypi.python.org/pypi/pip>`_.
 
 .. code-block:: bash
 
-   $> conda install numpy scipy cython h5py mercurial sympy
+   $> conda install numpy scipy cython h5py matplotlib psutil joblib six astropy
 
-pip
-^^^
+Alternatively, if you do not wish to use Anaconda, these can all be installed
+under ``pip`` by replacing ``conda`` with ``pip`` in the line above.  Some
+of these automatically come with Anaconda, but the above command
+will update these to the latest version if needed.
 
-If you do not elect to use the ``conda`` command, dependencies can
-also be installed via `pip <https://pypi.python.org/pypi/pip>`_.  Be
-aware that in order for `h5py` to properly compile you must first have
+Be aware that in order for ``h5py`` to properly compile you must first have
 `HDF5 <https://www.hdfgroup.org/HDF5/>`_ correctly installed (via
-`apt-get`, `brew`, or manual compilation) and in your respective
+e.g. `apt-get`, `brew`, or manual compilation) and in your respective
 environment paths.
 
+The optional galaxy/halo photometry computation in ``CAESAR``
+requires `python-fsps <http://dfm.io/python-fsps/current/>`_, which
+is a python wrapper for the ``FSPS`` fortran package.  Please follow
+their `installation instructions
+<http://dfm.io/python-fsps/current/installation/>`_ to install this.
+Furthermore, you will also need two other packages that are only
+available via ``pip``:
+
+.. code-block:: bash
+
+   $> pip install synphot extinction
+
+If you wish to use the MPI driver to run single instances of Caesar over
+many cores via MPI, it is also necessary to install ``mpi4py``:
+
 .. code-block:: bash
 
-   $> pip install numpy scipy cython h5py mercurial sympy
+   $> conda install mpi4py
+
+Note that ``CAESAR`` is natively OpenMP-parallel, and the MPI implementation
+may be system-specific. 
 
 ----
-   
+
 yt
 --
 
-``CAESAR`` relies on yt version 3.3 or above.  If you currently 
-have ``yt`` installed and its version number is less than 3.3 you
-must 
-`update <http://yt-project.org/doc/installing.html#updating-yt-and-its-dependencies>`_
-before ``CAESAR`` will function.  You can check your current ``yt``
-version via: 
+``CAESAR`` builds on the `yt <https://yt-project.org/>`_ simulation analysis toolkit.
+``CAESAR`` currently requires yt version >=3.3, though when yt-4.0 is released it will
+be updated to utilise this.
+
+We recommend installing ``yt`` via Anaconda:
 
 .. code-block:: bash
 
-    $> yt version
+   $> conda install -c conda-forge yt
+
+but other installation options are `described here <https://yt-project.org/#getyt>`_.
+
+If you already have ``yt``, you can check your version using ``yt version``, and
+`update <http://yt-project.org/doc/installing.html#updating-yt-and-its-dependencies>`_
+if necessary.
 
 ----
-   
+
 CAESAR
 ------
 
@@ -111,7 +132,7 @@ Once it finishes you should be ready to finally get some work done!
 Updating
 ========
 
-To update the code you simply need to pull down changes and reinstall:
+To update ``CAESAR`` simply pull the changes and reinstall:
 
 .. code-block:: bash