MultivariatePolynomial Class:

 - Added static Evaluate method.
 - Evaluate method now calls Term's Evaluate method.

Term Class:
 - Made Parse method public (was internal).
 - Added static and instance Evaluate methods.
 - Removed Term<T>.Empty.

Test Project
 - Added Test: TestParse_Term.
 - override TestParse_Term for Complex type.

Included bug fix from (non-generic) MultivariatePolynomial library.

MultivariatePolynomial<T>.Factor now working.
Tests for  MultivariatePolynomial<T>.Factor.
MultivariatePolynomial<T>.GCD now working for the univariate case.
Tests for MultivariatePolynomial<T>.GCD univariate case.