updated installation instructions for Python 3 only

INSTALL.rst

@@ -2,9 +2,8 @@
  Quick installation instructions for *MDPOW*
 =============================================
 
-MDPOW is compatible with Python 2.7 and 3.7+ and tested
-on Ubuntu and Mac OS. Python 2.7 is rock-stable and frozen but
-not officially supported anymore by the Python developers.
+MDPOW is compatible with Python 3.7+ and tested
+on Ubuntu and Mac OS.
 
 We recommend that you install MDPOW in a virtual environment.
 
@@ -29,28 +28,26 @@ GROMACS_.
 Conda environment with pre-requisites
 -------------------------------------
 
-To make a conda environment with the latest packages for Python 2.7
-and name it *mdpow*; this installs the larger dependencies that are
+Make a conda environment with the latest packages for Python 3.7 and
+higher with the name *mdpow*; this installs the larger dependencies that are
 pre-requisites for MDPOW::
 
- conda create -c conda-forge -n mdpow python=2.7 numpy scipy 'matplotlib<3.3' 'mdanalysis<2' 'mdanalysistests<2' pyyaml six
- conda activate mdpow  
- pip install gromacswrapper
+  conda create -c conda-forge -n mdpow  numpy scipy matplotlib mdanalysis pyyaml 'pandas>1.3.0'
+  conda activate mdpow
+  pip install gromacswrapper
 
+Install MDPOW with ``pip``::
 
-For Python 3.7 and up.
+  pip install mdpow
 
-*Note:* with Pandas version 1.3 there is an error with `Alchemlyb <https://github.com/alchemistry/alchemlyb>`_
-(see `issue #147 <https://github.com/alchemistry/alchemlyb/issues/147>`_) which will be fixed in Alchemlyb 0.5.::
+(This will install additional dependencies such as alchemlyb, which in turns
+needs pandas > 1.3.0.)
 
- conda create -c conda-forge -n mdpow python=3.7 numpy scipy 'matplotlib' 'mdanalysis' 'mdanalysistests' pyyaml six
- conda activate mdpow
- pip install gromacswrapper
 
 Installation from source
 ------------------------
- 
-Install from source::
+
+Instead of the pip-installation of MDPOW, you can also install from source::
 
  conda activate mdpow
  git clone https://github.com/Becksteinlab/MDPOW.git
@@ -91,5 +88,3 @@ A development install is useful while hacking away on the code::
 
  cd MDPOW
  pip install -e  .
-
-  

README.rst

@@ -1,6 +1,6 @@
-=================== 
+===================
  README for MDPOW
-=================== 
+===================
 
 |build| |cov| |docs|
 
@@ -35,15 +35,15 @@ Documentation
 * https://mdpow.readthedocs.io
 * `Tutorial`_ : computing the octanol-water partition coefficient of
   benzene (uses the `example files`_)
-  
+
 
 .. _Tutorial: http://mdpow.readthedocs.io/en/latest/init.html#tutorial-using-the-mdpow-scripts-to-compute-logpow-of-benzene
 .. _example files: https://github.com/Becksteinlab/MDPOW/tree/develop/doc/examples
 
 Installation
 ------------
 
-See `INSTALL`_ for detailed instructions. MDPOW currently supports Python 2.7 and Python 3.7 to 3.9.
+See `INSTALL`_ for detailed instructions. MDPOW currently supports Python 3.7 to 3.9.
 
 You will also need `Gromacs`_ (currently tested with versions 4.6.5,
 2018, 2020, 2021 but 2016 and 2019 should also work).
@@ -55,7 +55,7 @@ Development version
 If you want to install the development version, get the sources from
 GitHub (the development branch) ::
 
-  git clone https://github.com/Becksteinlab/MDPOW.git  
+  git clone https://github.com/Becksteinlab/MDPOW.git
 
 and Install from the checked out source::
 
@@ -71,7 +71,7 @@ Source code
 *MDPOW* is open source and published under the `GNU General Public License
 v3`_. Source code is available at https://github.com/Becksteinlab/MDPOW .
 
-.. _`GNU General Public License v3`: 
+.. _`GNU General Public License v3`:
    http://www.gnu.org/licenses/gpl-3.0.html
 
 Footnotes
@@ -91,5 +91,5 @@ Footnotes
 .. |docs| image:: https://readthedocs.org/projects/mdpow/badge/?version=latest
    :target: http://mdpow.readthedocs.org/en/latest/?badge=latest
    :alt: Documentation
-   
+
 .. _INSTALL: INSTALL.rst