Update page_types_lang.php

Rename 'Seitenlayout' (used for 'page type') to 'Seitentyp', because Layout is used for the page layout (!= page type).
Update pages_lang.php
Update permission_lang.php
Update pyro_lang_lang.php

add the english lang key for the extra field param "filter theme"
Update field.pyro_lang.php

add the missing closing tag "</ul>"
Merge pull request #2755 from dadaxr/patch-2

Update field.pyro_lang.php
Merge pull request #2754 from dadaxr/patch-1

Update pyro_lang_lang.php
Merge pull request #2751 from NicolasSchneider/patch-5

Update permission_lang.php
Merge pull request #2750 from NicolasSchneider/patch-4

Update pages_lang.php
Merge pull request #2749 from NicolasSchneider/patch-3

Update page_types_lang.php