NOTE from @kgaut : 

This is a quick and dirty port for d8, this readme file is not accurate. @see : https://www.drupal.org/node/2356469

How to make it works ?

  - download this module in modules folder (if you use composer : `composer require kgaut/potx`)
  - enable it : `drush en potx`
  - extract translation with drush : `drush @ALIAS potx single --include=modules/contrib/potx/ --modules=MYMODULE_MACHINE_NAME --api=8`

ABOUT
================================================================================

The goal of the Translation Template Extractor project is to provide 
command line and web based Gettext translation template extractor 
functionality for Drupal. These translation templates are used by 
teams to translate Drupal to their language of choice. There are 
basically two ways to use the contents of this project:

 * Copy potx.inc and potx-cli.php to the directory you would like to 
   generate translation templates for and run php potx-cli.php. 
   The translation templates will get generated in the current 
   directory.

 * Install the module on a Drupal site as you would with any other 
   module. Once potx module is turned on, you can go to the 
   "Extract" tab on the "Translate interface" administration interface, select 
   the module or modules or theme or themes you want to have a translation
   template for, and submit the form. You will get one single template file
   generated.

   Note: If you only get a white browser screen as response to the 
   extraction request, the memory limit for PHP on the server is probably 
   too low, try to set that higher.

The module also includes optional Coder (http://drupal.org/project/coder)
integration, allowing you to spot translatability errors in modules while
doing your regular code review.

USING potx-cli.php ON THE COMMAND LINE
================================================================================

Translation templates can easily be created by running the potx-cli.php
script on all source files that contain translatable strings.

  1. Copy the potx-cli.php and potx.inc to whatever folder you
     would like to generate template files in.
  2. Run 'php potx-cli.php' and the script will autodiscover
     all possible files to generate templates for.
  3. Translation templates are generated in this folder, if you
     have the proper rights to create files here.
     
You can try 'php potx-cli.php --help' to get a list of more options.
  
The contents of files depend on the mode you use. By default, one
single general.pot file will be generated. You can use the "core"
mode to generate Drupal core templates (one file per directory, repeated
usage of the same string in multiple directories folded into general.pot,
.info files folded into general.pot). Or you can use the "multiple" mode
which is similar to the "core" mode, but .info files are folded into
their module template files.

In case of "core" and "multiple" mode, the generated general.pot will
contain strings that occur more than once in the source files. This will help 
translators to maintain a single translation for them. 

CREDITS
================================================================================

Command line extractor functionality orignally by 
  Jacobo Tarrio <jtarrio [at] alfa21.com> (2003, 2004 Alfa21 Outsourcing)

Greatly optimized by 
  Brandon Bergren (2007)

Currently maintained by 
  Gabor Hojtsy <gabor [at] hojtsy.hu>