remove duplication in tactic

document 'case_distrib'

tuning

generate 'case_distrib' for Ctr_Sugars

more metrics, with integer coordinates for layout; initial coordinates: center x as in old browser; Layout.pendulum/collapse: proper downwards range; distance as in old browser (see spaceBetween); move offset as in old browser; more careful comparison wrt. 0.0 (this is IEEE double, not int);

tuned;

misc tuning;

explicit Layout.Point; tuned signature; tuned;

tuned comments;

tuned;