Remove trailing whitespaces (#361)

doc/development/contribution/style.rst

@@ -8,12 +8,12 @@ Python code
 
   Use `flake8`_ to check for conformance problems. The project includes a setup.cfg file
   with a default configuration for flake8 that excludes migrations and other non-relevant
-  code parts. It also silences a few checks, e.g. ``N802`` (function names should be lowercase) 
-  and increases the maximum line length to more than 79 characters. **However** you should 
+  code parts. It also silences a few checks, e.g. ``N802`` (function names should be lowercase)
+  and increases the maximum line length to more than 79 characters. **However** you should
   still name all your functions lowercase [#f1]_ and keep your lines short when possible.
 
 * Our build server will reject all code violating other flake8 checks than the following:
-  
+
   * E123: closing bracket does not match indentation of opening bracket’s line
   * F403: ``from module import *`` used; unable to detect undefined names
   * F401: module imported but unused

doc/development/setup.rst

@@ -118,8 +118,8 @@ Then execute ``python -m smtpd -n -c DebuggingServer localhost:1025``.
 
 Working with translations
 ^^^^^^^^^^^^^^^^^^^^^^^^^
-If you want to translate new strings that are not yet known to the translation system, 
-you can use the following command to scan the source code for strings to be translated 
+If you want to translate new strings that are not yet known to the translation system,
+you can use the following command to scan the source code for strings to be translated
 and update the ``*.po`` files accordingly::
 
     make localegen