Add new translator Semantics Online Bibliographies.js

This translator can handle two websites:
 * BLLDB = online version of the  Bibliography of Linguistic Literature (BLL)
 * BDSL = online version of the Bibliographie der deutschen Sprach- und Literaturwissenschaft

see #811, which are avaialable in German and English.

Some remarks:
 * The test cases are only working if you replace the `vid` parameter with a current session key.
 * I feel that all information from the classification and so on are just too much to add everything as tags. Moreover, I have no idea how to restrict to not more than 10 good tags. Thus, I don't add any tags, but everything should be searchable in the snapshot.
It's not so much about what it means, it's more about what the name of the cataloging software that is used. In this case semantics lists their product as "Visual Library", so "semantics Visual Library" makes the most sense to me and  provides the most reasonable way to identify a translator that recognizes that system. Looking at the BDSL/BLLDB page and following the link to semantics website, I wouldn't think to look for an "Online Bibliographies" translator (though granted that semantics being in the name helps)

I would put BDSL/BLLDB first and the name of the translator in the parentheses. The name of the database is what's relevant to the user and should be the most prominent data in that field. The name of the translator is helpful for us for troubleshooting purposes.