always close derivation at the bottom of forked proofs (despite increased non-determinism of proof terms) -- improve parallel performance by avoiding dynamic dependency within large Isar proofs, e.g. Slicing/JinjaVM/SemanticsWF.thy in AFP/bf9b14cbc707;

simplified proofs

tuning

misc cleanup;

tuned signature;

use inlined session name as title for charts; tuned signature;

tuned signature;

charts for future task runtime statistics;

merged

more uniform permissions;