more robust cleanup; more defensive timing value;

isabelle.Build uses ML_Process directly; isabelle_process is for batch mode only; removed unused feeder (already part of "isabelle console");

tuned;

print timing like lib/scripts/timestop.bash;

prefer explicit locale;

bash process with builtin timing;

elapsed time in milliseconds (cf. Time.now in Poly/ML);

support for timing of the managed process;

tuned;

proper support for RAW_ML_SYSTEM;

tuned signature;

separate Isabelle_Process.init_options after Options.load_defaults, notably for "isabelle console";