static type for Library.using: avoid Java 11 warnings on "Illegal reflective access";
more uses of "using";

discontinued unused / untested distinction of separate PIDE modules;

proper SHA1 digest as annex to heap file: Poly/ML reads precise segment length;

tuned signature;

less authentic SHA1.digest: trust Scala side on blobs and avoid re-calculation via Foreign Language Interface, which might be a cause of problems;

prefer abstract datatype -- in accordance to ML version;

tuned signature;

explicit module UTF8;

tuned signature;

maintain set of source digests, including relevant parts of session entry;

more explicit java.io.{File => JFile};

more SHA1.digest operations;

separate compilation of PIDE vs. Pure sources, which enables independent Scala library;

explicit indication of modules for independent Scala library;

tuned signature;

explicit type SHA1.digest;

digesting strings according to SHA-1 -- Scala version;