support multiple webservers: Apache or Nginx;

tuned;

clarified signature: explicit type isabelle.Url to avoid oddities of java.net.URL (e.g. its "equals" method);

unused;

enforce rebuild of Isabelle/Scala + Isabelle/ML;

updated to postgresql-42.7.1;

updated to sqlite-jdbc-3.45.0.0, including slf4j-1.7.36;

update to llncs-2.23; update src/Doc/Demo_LLNCS to include the new mandatory section "Disclosure of Interests";

clarified bootstrap;

clarified directories;