tuning punctuation in messages output by Isabelle

tuning whitespace in output syntax

gnuplot presentation similar to former isatest-statistics;

tuned;

statistics from session build output;

more uniform output;

added [simp] lemmas

more robust HTML rendering of hidden control symbols: Vacuous font bypasses minimal font-size restrictions of common browsers, transparent colour imitates hidden visibility while copy-paste still works;

merged

active jEdit actions;