Charter Amendment (Sixth Draft) to amend the Charter of the City and County of San Francisco by amending Section 4.105 and adding Section 4.135 to establish an Independent Historic Preservation Commission, appointed by the Mayor, subject to the approval of the Board of Supervisors and meeting certain specified qualifications, with authority to recommend approval, disapproval or modification to the Board of Supervisors of landmark, and significant or contributory building designations under the P