Changes

Changes from Mercurial (hg http://isabelle.in.tum.de/repos/isabelle/ default)

Summary

1. enforce full build, after significant changes in Isabelle/Scala;
2. clarified compiler options: show relevant warnings;
3. tuned --- avoid compiler warnings;
4. clarified signature --- fewer warnings;
5. clarified signature --- fewer warnings;
6. tuned --- fewer warnings;
7. more robust ordering (see also 88c96e836ed6);
8. proper scala.collection.immutable;
9. tuned --- fewer warnings;
10. tuned --- fewer warnings;
11. tuned;
12. tuned --- fewer warnings;
13. tuned --- fewer warnings;