Test IO::Handle.seek
Test IO::Handle.seek

Fixes #219

It currently throws when seeking past start of file, but doesn't complain
about seeking past end. I left throwage tests commented out for now,
will make figuring out the failure modes as part of IO improvement stuff.

bitrauser/roast,dogbert17/roast,dogbert17/roast,perl6/roast,bitrauser/roast