split isar_step into isar_step, fix, assms; made isar_proof explicit; register fixed variables in ctxt and auto_fix terms to avoid superfluous annotations
syntax: glob
*~
*.class
*.jar
*.orig
*.rej
.DS_Store
syntax: regexp
^contrib
^heaps/
^browser_info/
^doc/.*\.dvi
^doc/.*\.eps
^doc/.*\.pdf
^doc/.*\.ps
^src/Tools/jEdit/dist/