enforce use of spaces for indentation

doc/yas-doc-helper.el

@@ -162,6 +162,7 @@
 
 (provide 'yas-doc-helper)
 ;; Local Variables:
+;; indent-tabs-mode: nil
 ;; coding: utf-8
 ;; End:
 ;;; yas-doc-helper.el ends here

yasnippet-debug.el

@@ -125,6 +125,7 @@
 
 (provide 'yasnippet-debug)
 ;; Local Variables:
+;; indent-tabs-mode: nil
 ;; byte-compile-warnings: (not cl-functions)
 ;; End:
 ;;; yasnippet-debug.el ends here

yasnippet-tests.el

@@ -822,6 +822,7 @@ add the snippets associated with the given mode."
 
 (provide 'yasnippet-tests)
 ;; Local Variables:
+;; indent-tabs-mode: nil
 ;; lexical-binding: t
 ;; byte-compile-warnings: (not cl-functions)
 ;; End:

yasnippet.el

@@ -4595,6 +4595,7 @@ can more or less safely rely upon them.")
 (provide 'yasnippet)
 ;; Local Variables:
 ;; coding: utf-8
+;; indent-tabs-mode: nil
 ;; byte-compile-warnings: (not cl-functions)
 ;; End:
 ;;; yasnippet.el ends here