Update install doc and add a faq entry.

- Removing python 2.7.15 section from virtualenv python install guide.
- New FAQ entry about OpenMP issue on MacOS X (referenced in the
  appropriate docs).

gen_doc/bin_pkgs/macosx/README_install_part.html

@@ -16,5 +16,12 @@ To avoid this issue you can <i>symlink</i> you matlab path into /Applications (t
 </code></pre>
 
 
-After installing the package, you'll need to restart your Matlab or Python session in order to take into account the new configuration of your environment. Of course if you want to use only the Python wrapper you don't need to worry about setting the PATH environment for Matlab and conversely. But note that if later you change your mind and want FAµST for the both languages you'll just need to relaunch the installer.
-
+<b>After installing the package: </b>
+<ul>
+  <li>
+you'll need to restart your Matlab or Python session in order to take into account the new configuration of your environment. Of course if you want to use only the Python wrapper you don't need to worry about setting the PATH environment for Matlab and conversely. But note that if later you change your mind and want FAµST for the both platforms you'll just need to relaunch the installer.
+</li>
+<li>
+  On Mac OS X you might need to install OpenMP for pyfaust to work, for further information please look at this <a href="https://faustgrp.gitlabpages.inria.fr/faust/last-doc/html/FAQ.html#py_four">FAQ entry</a>.
+</li>
+</ul>

gen_doc/faq.md

@@ -8,6 +8,7 @@
 [1. How can I launch the integrated unit tests of pyfaust?](#py_one)  
 [2. How to launch the demos with pyfaust?](#py_two)  
 [3. How to run the PALM4MSA algorithm in a step-by-step fashion?](#py_three)  
+[4. Why do I get the error 'Library not loaded: @rpath/libomp.dylib' when I use pyfaust on Mac OS X and How to fix it?](#py_four)  
 
 **About matfaust:**  
 [1. Why did I get a file-not-found error when running demos or examples?](#mat_one)  
@@ -248,4 +249,13 @@ Below is an example of output you should obtain running the script (into which y
 	Relative error comparing the final Fausts obtained either by in step-by-step PALM4MSA versus all-iterations-at-once PALM4MSA:  2.1117031467008879e-16
 
 
+\anchor py_four
 
+## Why do I get the error 'Library not loaded: @rpath/libomp.dylib' when I use pyfaust on Mac OS X and How to fix it?
+
+Well pyfaust has many dependencies, certain of them are built within the pyfaust shared library, other are linked dynamically as is OpenMP. So to use pyfaust you need to install OpenMP on Mac OS X. We advise to install it through MacPorts because pyfaust is compiled and linked using the Mac Ports provided version of OpenMP.
+To install MacPorts go on their [website](https://www.macports.org/) and download the pkg, that's pretty straightforward.
+Once Macports is installed, launch a terminal and type this command:
+  
+  	sudo port install libomp
+  	sudo port -f activate libomp

gen_doc/install_pyfaust_in_venv.md

@@ -35,35 +35,7 @@ As a result, you should see the version of pyfaust installed if all went properl
 
 \note In the virtual environment python is necessarily python version 3 (because the creation was made through python3 above).
 
-Python 2.7.15+
-=============
-
-You need at first to install virtualenv:
-
-	$ pip install virtualenv
-
-\note Take care to use the good version of pip (corresponding to the python 2.7 version you want to use).
-
-Then you can create your python 2.7 virtual environment:
-
-	$ virtualenv test_pyfaust-2.7
-
-The next is all the same as for python 3, you enter the virtual env.:
-
-	$ source ./test_pyfaust-2.7/bin/activate
-
-\note For Windows users the command is rather:
-
-	C:\> call .\test_pyfaust-2.7\Scripts\activate
-
-Install the pip wheel package:
-
-	$ pip install pyfaust-*.whl
-
-And finally launch the version test command to check the whole process:
-
-	$ python -c 'from pyfaust import version; print(version())'
-
+\note On Mac OS X you might need to install OpenMP for pyfaust to work, for further information please look at this [FAQ entry](https://faustgrp.gitlabpages.inria.fr/faust/last-doc/html/FAQ.html#py_four).
 
 Anaconda
 ========