no longer open PolyML -- to avoid surprises within the global name space;
recovered some important PolyML bindings (NB: print and makestring cannot be rebound without loosing infinite overloading);
Checklist for official releases
===============================
- test mosml, polyml-5.2, polyml-5.1, polyml-5.0;
- test sparc-solaris, x86-solaris;
- test ProofGeneral;
- test Scala wrapper;
- check HTML header of library;
- check CTRL-C, SIGINT in tty (also for external processes);
- check persistent sessions with PG and Poly/ML 5.x;
- Admin/update-keywords;
- check ANNOUNCE, README, INSTALL, NEWS, COPYRIGHT, CONTRIBUTORS;
- update https://isabelle.in.tum.de/repos/website;
- maintain Docs:
doc-src/Dirs
doc/Contents
- maintain Logics:
build
lib/Tools/makeall
lib/html/library_index_content.template