Importer, After theme setup (Werner), Addqueryparameter, Widget bottom margin

* Importer; ensured files are loaded (required); taxonomy, image
* Ensure site settings exist does "less"; delegates implementation to
pluggable action "nxs_reinitializetheme"
* Added "nxs_reinitializetheme_finished" pluggable extension, allowing
implementations to implement for example redirects.
* Addqueryparameter url encodes the value
* Widget bottom margin now is configurable