Facets Range Dropdowns

Provides processors and a widget to handle ranges with dropdowns in facets.

This module mainly improves upon the Range slider widget provided by the Facets module in its Facets Range Widget submodule and the Range dropdowns widget provided by https://www.drupal.org/files/issues/dropdowns-range-widget-2928069-2.patch.

The Range dropdowns widget provided by the patch extends the Range slider widgets which seems to be an odd design choice because it leads to all kinds of complications. It seems to be better to provide dropdowns in a similar way as the default Dropdown widget provided by Facets.

To speed up development of a Range dropdowns widget this separate module brings together best of both worlds. Once a stable widget is available it might be better to merge this into the Facets module itself.