Release of v5.1.1-alpha1

Move all banners to GitHub. Adds library phpspreadsheet to JCB. Adds import item example to demo component. Updates the Superpower class with the GetRemote class in the plugin. Ensures the super power autoloader triggers the correct repositories.

libraries/phpspreadsheet/vendor/maennchen/zipstream-php/guides/Nginx.rst

@@ -0,0 +1,16 @@
+Usage with nginx
+=============
+
+If you are using nginx as a webserver, it will try to buffer the response.
+So you'll want to disable this with a custom header:
+
+.. code-block:: php
+    header('X-Accel-Buffering: no');
+    # or with the Response class from Symfony
+    $response->headers->set('X-Accel-Buffering', 'no');
+
+Alternatively, you can tweak the
+`fastcgi cache parameters <https://nginx.org/en/docs/http/ngx_http_fastcgi_module.html#fastcgi_buffers>`_
+within nginx config.
+
+See `original issue <https://github.com/maennchen/ZipStream-PHP/issues/77>`_.