This imports magic.py from file-magic and merges magic_wrap.py into
it...

This also updates detect_from_filename to try w/ _COMPRESS, and if
it returns an error, normal mode.  This is necessary as [some?] zip
files can be decompressed by gzip, but throws an error...

We were only using the ed448 code, and cryptography requires rust
to compile, and contains a LOT of other code, while edgold is much
smaller, and doesn't require a rust compiler, and will work on more
systems..  Keep around an old identity generated from cryptography
to make sure the two libraries are compatible.

one minor issue is that the identity object gets dump'd twice..

fix up code to pass all the tests...

changes..