The ghost of Raj Rajaratnam still haunts hedge funds. Some make employees sign pledges that they’ve not acted on illicit tips, others snoop on their traders with keystroke-reading software. At the compliance meetings everybody has these days, prison isn’t an off-the-wall topic. The illegal-trading probes that netted crooks at more than a dozen funds may have reached an unofficial finale with a whimper last week -- a deal allowing SAC Capital Advisors LLC’s...