Remove Twitter; use Mastodon (#1859)

- update fontawesome to 6.4.2 (gains mastodon) by copy new css to old css
- add new webfonts
- refactor "fa" (fontawesome) to "fa-brands" for brands (github and twitter)

web/app/views/main.scala.html

@@ -74,11 +74,11 @@
 	                lobid-resources | ein Dienst des <a href='https://www.hbz-nrw.de/produkte/linked-open-data'>hbz</a>
                 </span>
                 <span class="pull-right">
-	                <a href="http://lobid.org/warranty">Gewährleistung</a> | 
-	                <a href="https://www.hbz-nrw.de/impressum">Impressum</a> | 
+	                <a href="http://lobid.org/warranty">Gewährleistung</a> |
+	                <a href="https://www.hbz-nrw.de/impressum">Impressum</a> |
 	                <a href="https://github.com/hbz/lobid/blob/master/conf/Datenschutzerklaerung_lobid.textile">Datenschutz</a> |
-	                <a href="https://twitter.com/lobidorg"><i class="fa fa-twitter" aria-hidden="true"></i> Twitter</a>&nbsp; 
-	                <a href="https://github.com/hbz/lobid-resources"><i class="fa fa-github" aria-hidden="true"></i> GitHub</a>&nbsp; 
+                    <a href="https://openbiblio.social/@@lobid"><i class="fa-brands fa-mastodon" aria-hidden="true"></i> Mastodon</a>&nbsp;
+	                <a href="https://github.com/hbz/lobid-resources"><i class="fa-brands fa-github" aria-hidden="true"></i> GitHub</a>&nbsp;
 	                <a href="http://blog.lobid.org"><i class="fa fa-pencil" aria-hidden="true"></i> Blog</a>
                 </span>
               </div>