Société Générale announced that its first-quarter net income decreased 20% from the same quarter a year earlier.  The French bank said that its first-quarter net income fell due to unloaded assets and booking a charge on the cost of its debt.  Société Générale’s stock has declined by about 60% in the last year. Net income dropped to 732 million euros ($963 million) in the first three months of the year.  Revenue decreased 4.7%, to 6.3 billion euros.  Without the charge for the revaluation...