§ 21. Public or municipal purpose and general welfare defined. Notwithstanding any other provision of law, the terms "public or municipal purpose," and "general welfare," as used in this article, shall each include the promotion of education, art, beauty, charity, amusement, recreation, health, safety, comfort and convenience, and the promotion, creation, development or expansion of business, commerce, industry or job opportunities, and all of the purposes enumerated in sections twenty, twenty-a, twenty-b, and twenty-e.