Taxonomy Facets 3.0.0-rc3

Since 3.0.0-rc2:
- New submodule taxonomy_facets_export: facet URL enumerator + Drush command.
- New submodule taxonomy_facets_tome: Tome Static integration.
- New submodule taxonomy_facets_simple_sitemap: Simple XML Sitemap integration.
- Page-count estimator (batch) for Tome and Sitemap, with admin guidance.
- Default base path changed from 'listings' to 'browse'.
- Admin settings forms for Tome and Sitemap; label cleanups.
- Fix FacetContext memoization in Tome static export.
- Fix Functional tests after the base_path rename.