AssertWellDefined -- Option to verify that a constructed DG algebra map respects differentials

When set to true, the constructor checks that the output DGAlgebraMap or the resulting ComplexMap actually commutes with the differentials up to the working degree. This is a false by default because the check can be expensive for large acyclic closures; set it to true when debugging a DG map that behaves unexpectedly.

Functions with optional argument named AssertWellDefined:

• toComplexMap(...,AssertWellDefined=>...) -- see toComplexMap -- Construct the ComplexMap associated to a DGAlgebraMap