2010-01-04 ago discontinued special HOL_USEDIR_OPTIONS;
2009-07-20 ago replaced usedir option -Q by more fine-grained -q;
2009-05-31 ago uniform treatment of shellscript mode;
2009-01-27 ago HOL_USEDIR_OPTIONS: -Q false, giving up parallel proofs for now due to memory shortage;
2008-10-23 ago switched parallel sessions to polyml-5.2.1;
2008-06-06 ago switched to Poly/ML 5.2;
2008-03-24 ago replaced obsolete /usr/proj by /home;
2008-03-06 ago removed obsolete THIS_IS_ISABELLE_BUILD feature;
2007-12-05 ago make at64 non-experimental