Initial commit.

Creating the standard Autotools infrastructure and adding the
first extensions (the Hello, World! provided by the wizard).

extensions/example/metadata.json

@@ -0,0 +1 @@
+{"uuid": "example@gnome-shell-extensions.gnome.org", "name": "Hello, World!", "description": "An example extension to show how it works. Shows Hello, world when clicking on the top panel.", "shell-version": [ "2.91.5" ]}