The city of Baltimore has declared today Frank Zappa Day in honor of the iconoclastic rock musician and composer, born there on Dec. 21, 1940. He would have been 69 years old, and probably doing what he always did best — shredding convention and exploding the notion of what you can and can’t do with the same old tools of production. Just check out what he did on the Steve Allan show in 1963, where he plays a bicycle…