fix fix usage of insert! and remove!
Add support for '^' in 'sign'
Fix 'child?' in RecursiveAggregate
fix usage of insert! and remove!
docfix typos: Thanks Frédéric Chapoton
Better recognize commutative factors
Minor cleanups
Add coercion to OutputForm to FakePolynomial
Add factorization for XDPOLY
Documentation and comment fixes