batch-oggencode.rb: ignore return value of find command
batch-oggencode.rb: s/Converted/Sucessfully processed/
batch-oggencode.rb: add --diff, to compare files using cmp
batch-oggencode.rb: instead of having --copy and --diff, have one option --utility taking the desired mode as an option
batch-oggencode.rb: s/--no-strip-file-name/--no-mangle-filename/g, add some text to the usage message.