message: Add first stab at introducing the format options we want.
  See
diff: @@ -5,8 +5,17 @@ use structopt::StructOpt;
  /// Fathom DDL interpreter to provide tools to inspect and query binary files.
  #[derive(StructOpt, Debug)]
  pub struct Cli {
  - /// The pattern to look for
  - pattern: String,
  + /// --format=NAME is an optional argument for specifying the name
  + /// of the format description in the installed catalog, for
  + /// example "opentype", that will be used to process the files.
  + #[structopt(long)]
  + format: String,
  + /// --format-file=FILE is an optional argument for specifying the
  + /// file containing the format description, for example
  + /// "path/to/myformat.ddl", that will be used to process the
  + /// files.
  + #[structopt(long)]
  + format_file: PathBuf,
  /// The path to the file(s) to parse
  #[structopt(parse(from_os_str))]
  files: Vec<PathBuf>,
  