Propagate 'CoercibleTo(OutputForm)' to aggregates.
Generalize indexed product.
Update comments.
Make NonNegativeInteger into SemiRing.
Add SemiRing i SemiRng to boo-nilcat.spad.
Fix 'smaller?' in FMCAT.
Spelling corrections.
Add computation theory framework.
Better handling of trigonometric integrals.
Comment fix.