rename variable in binder, not just in body

swap Vampire's Skolem arguments to bring them in line with what E and metis's new skolemizer do (helps Isar proof reconstruction in some cases)

tuned comment

NEWS: ML runtime statistics;

merged

more interesting fields;

always enable Future.ML_statistics where this makes sense -- runtime overhead should be negligible;

improved Monitor_Dockable, based on ML_Statistics operations; tuned signature;

get rid of two-year-old hack, now that the "metis" skolemizer no longer gets stuck in HO unification

avoid explosion in higher-order unification algorithm

avoid repeated calls to metis from "resolve_tac" in case of ultimate failure

tuned comment

merged

added standard_frames convenience;

some grouping of standard fields; tuned signature;

some support for chart drawing;

some support for ML statistics content interpretation;

moved files;

moved files;

ML runtime statistics: read properties from build log;

support File.read_gzip as well, in accordance to File.write_gzip; tuned signature;

inline ML statistics into build log;

removed outdated comment;

enable Z3 for full test (cf. 6f48853f08d5);

removed old, unused code

removed whitespace

removed duplicate code

use rpair to avoid swap