Expose CSS namespace

[mootari]

The CSS namespace placeholder __ns__ is currently replaced via rollup, but the replacement value is not exposed anywhere. In order to write custom CSS that targets the library's widgets, one has to first retrieve the scope via the following awkward snippet:

Inputs.text().classList[0]

Suggested solution: Expose the scope via a readonly property or getter e.g. Inputs.namespace, Inputs.ns or Inputs.scope.