Changes

Summary

1. more robust;
2. tuned message;
3. NEWS;
4. more documentation;
5. tuned documentation;
6. more documentation;
7. added option -r: support more robust consolidation of local clones with varying names;
8. clarified backup;
9. removed somewhat pointless option -R: more careful inspection of hgrc is required in practice;
10. proper proof body context for Simplifier plugins (solvers, loopers, ...) -- avoid crash due to Subgoal.FOCUS (before e58bc223f46c);
11. more robust bound_fixes: external name does appear in "fixes" name space and could clash with direct fixes (e.g. via Subgoal.FOCUS within a global context);
12. tuned signature;