Use exception less ambiguously
Change decoding scheme

It looks like newsgroup messages are generally stored in Latin 1,
not UTF-8.  I should eventually rewrite this to be character set
independent, but for now, let's assume text is Latin 1.
Don't get the same message multiple times

This involved quite a drastic refactoring of the existing code.
Failed attempt at stitching
Revert "Failed attempt at stitching"

This reverts commit cdbcdfa1ea45887a13f6a90994744b7c38ae502c.
Successful attempt at stitching, SHA1 verified