(Combinatorial) Free modules: cleanup, abstraction into categories, and functorial constructions

[nthiery]

• Deprecates CombinatorialAlgebra?
• Abstracts some of the generic code into ModulesWithBasis?, Algebras, ...
• Implements the functorial constructions: tensor and cartesian product
• Stronger type checking, use UniqueRepresentation?
• Disabled dangerous conversions (see doc of _element_constructor), strict contains
• Naming cleanup: _term -> term, repr -> _repr_, _element_class -> element_class _combinatorial_class -> _basis_keys
• New methods: monomial, sum_of_terms, sum_of_monomials, term_or_zero_if_none, from_vector, _repr_term, _repr_option_bracket
• More interesting an_element, using heuristics
• Handle non sortable objects in repr
• Implements sage.categories.poor_man_map.PoorManMap? for maps between sets which are not modelled by parents.
• This is used to make term and sum_of_monomial into maps, with codomain and composition.

Depends on the category patches. See  http://sagetrac.org/sage_trac/wiki/CategoriesRoadMap.

[nthiery]

Adds TestSuite?.run call, and implements equality for PoorManMap?'s. Apply only this one.

[hivert]

Last version of the file from combinat patch server.

[hivert]

Apply only the last patch trac_6136-categories-freemodule-nt.2.patch

Note: it breaks some doctests which are corrected in #6137 (See  http://sagetrac.org/sage_trac/wiki/CategoriesRoadMap)

Ready to go.

Cheers,

Florent

[hivert]

Correct version