All zoning ordinances or parts of zoning ordinances inconsistent with the provisions of this chapter are hereby repealed. It is expressly provided that the provisions of this chapter shall not affect any act done, contract executed or liability incurred prior to its effective date, or affect any suit or prosecution pending or to be instituted to enforce any rights, rule, regulation or ordinance, or part thereof, or to punish any violation which occurred under any prior zoning ordinance or regulation. In the event any violation has occurred under any prior zoning regulation or ordinance of Denver Borough, prosecution may be initiated against the alleged offender pursuant to the provisions of said prior zoning regulation or ordinance, and the provisions and penalties provided in said prior zoning regulation or ordinance shall remain effective as to said violation.