Introduced 11ty

Set new version based on all changes since last version change, which was 0.4.2.

Removed obsolete devDependencies, now only using 11ty and sass.

Update to package.json fields

- New sass version
- Update to project links
- Rearranged fields
- New commands for 'scripts' that include changes from branch testing-npm-scripts
- Added field 'private' to prevent publishing by mistake

Added configuration for 11ty to reflect previous behaviour from gulp.

- Moved source/templates/demo/data.json to source/screens/demo.json so it can be used
- Fixed demo template so it can use the data source
- Removed source/data/demo.json which was not used

source/data/demo.json

@@ -1,22 +0,0 @@
-{
-  "demo": [
-    {
-      "demo1": "1",
-      "demo2": "2"
-    },
-    {
-      "demo1": "1",
-      "demo2": "2"
-    },
-    {
-      "demo1": "1",
-      "demo2": "2"
-    }
-  ],
-  "test": [
-    {
-      "test1": "3",
-      "test2": "4"
-    }
-  ]
-}