adding command line help
adding command line help

git-svn-id: aa3aca99a267bb8c861e7217b855a78ec78db5b0@17 1b3fd781-6a22-fc33-3c53-039dc0e80cbb

julioa/pngtastic,aharpour/pngtastic,aharpour/pngtastic,julioa/pngtastic,aharpour/pngtastic,depsypher/pngtastic,julioa/pngtastic