Post-Gazette: The spotlight on energy issues, from the Deepwater Horizon disaster in the Gulf to the debate over development of Marcellus Shale gas wells, illuminates the clear philosophical differences between Pennsylvania’s Senate candidates. From drilling to the overall debate on global warming, Republican Pat Toomey and Democrat Joe Sestak take contrasting positions. In keeping with his general hostility toward big government, Mr. Toomey is skeptical of proposals to expand federal …