clarified modules;

clarified signature: prefer explicit types;

more accurate Sessions.Info.session_prefs: cover relative changes wrt. statically declared options;

clarified signature: more explicit type Options.Spec, which incorporates all variants of Options.+;

tuned output;

clarified signature: more explicit types;

clarified signature: prefer static types;

clarified signature (again, see also 8c64e51d9dde and 268bf61631ec);

tuned signature;

more operations, thanks to Jsoup;

discontinued apache-commons in favour of jsoup, which is smaller and more useful;

more accurate shasum_meta_info;

tuned signature;

support "isabelle options -l -t TAGS";

NEWS;

clarified signature;

tuned;

avoid hard-wired stuff (see also 78f2475aa126);

clarified tags;

clarified session prefs (or "options" within the database);

tuned signature;

tuned comments;

unused (see 268bf61631ec);

clarified exported options;

clarified signature;

do not export connection details (password etc.);

support option tags;

use simplifier to classify the missing assumptions in Sledgehammer's abduction mechanism

don't try to falisfy goals with schematics

enforce rebuild of Isabelle/ML;