idgames_sync.pl: document return values from sync() method
idgames_sync.pl: start implementing %idgames_filelist for issue #5

- Use %idgames_filelist as the debug counter instead of a separate
  counter
idgames_sync.pl: remove extra closing parenthesis
idgames_sync.pl: fixed references to total_synced_files
idgames_sync.pl: don't warn about file size mismatch for metafiles
idgames_sync.pl: Delete non-archive files with --prune; fixes #5