Module for identification of a document. "Identification"
means determining, by querying modules successively, what the format
of a document is. The Bytestream module is always queried last,
so a document will by identified as a Bytestream if all else fails.
Perform identification on a file. The file is parsed by
each of the modules in the module list until one
declares that the file is well-formed. It is assumed
that there is a module in the list (normally Bytestream
at the end) which will always consider a file well-formed.