Notice of Filing of Proposed New Rule G-42, on Political Contributions and Prohibitions on Municipal Advisory Activities; Proposed Amendments to Rules G-8, on Books and Records, G-9, on Preservation of Records, and G-37, on Political Contributions and Prohibitions on Municipal Securities Business; Proposed Form G-37/G-42 and Form G-37x/G-42x; and a Proposed Restatement of a Rule G-37 Interpretive Notice