SAN FRANCISCO (AP) - Actor-director Rob Reiner campaigned Thursday against Proposition 75, a ballot initiative pushed by Gov. Arnold Schwarzenegger that would require public employee unions to get permission to use members' dues for political purposes. Reiner, a Democrat and longtime political activist often mentioned as a potential challenger to Schwarzenegger, told an audience that Prop. 75, known as "paycheck protection" by its supporters, was designed purely to stifle political speech. "The things I care about - education, health care, energy, environment - I need, we all need, to have everybody's voice heard," Reiner told a small audience of teachers,...