Within the districts established by this chapter, there exist, may exist or will exist lots, uses of land, and/or characteristics of use which were lawful before this chapter was enacted but which would be prohibited, regulated or restricted under the terms of this chapter. Inasmuch as these nonconformities are, by definition, alien to the zoning scheme of the districts created under this chapter, it is the intent of this chapter to restrict, rather than increase, such nonconformities.