rename location_color to goal_color and lighter_location_color
to premise_color

defaults are "yellow" and "gold" and if you don't like them change them

are not the actual goal.

It's still madness. We shouldn't open our quantifiers every time
we redraw screen. This needs to be fixed.

with old Why3 version where sessions do not contain goal shapes

In addition,
- scan below conjunctions in case there are equalities there too,
- ignore predicate variables and "true" axioms,
- output hypotheses in the proper order,
- explicitly remove NonTrivialRing since it now survives the filtering.