Scraper for BfN - WISIA

Scraping the https://www.wisia.de/ (Wissenschaftliches Informationssystem zum Internationalen Artenschutz).

WISIA contains taxonomic information and protection status for protected species.

	number
Verfügbare Namen	111848
gültige Namen	35443
Synonyme und Schreibweisen	61500
landessprachliche Namen	14905

The scraper collects the title from "gültige Namen", and amends with "landessprachliche Namen" if found.

7859 species reducing to 5729 unique "gültige Namen" are found by the wildcard search without selecting a "Regelwerk" under which the species is regulated. An additional search collecting over each Regelwerk results in a total of 22809 results.

A search with "taxon=" (empty) returns more results as a search with wildcard "taxon=*". If the latter is a subset of the first, is not clear.

Further fields to be included in the metadata scheme need to be discussed.

Closes #152 (closed), contributes to #149 (closed)