The Redlands city general plan and this code shall be amended forthwith to conform with the requirements of measure N. To the extent that any policy or provision of measure N is not self- executing the city council shall promptly enact such regulation and ordinances as may be necessary to carry out the purposes, intent and directives hereof. The provisions of measure N are expressly declared to be minimum requirements. (§ 4 of measure N, passed by voters 11-3-1987: § 14 of proposition R, passed by voters 11-7-1978)