Class encoding fails if input only contains one line without new line?

[proycon]

Discovered by @fkunneman; output file was only 2-bytes (the initial null byte and version marker).

Input text was just: prachtig apparaat en droogt goed kreukelvrij fijn de verlichting binnenin voelt heel robuust en ziet er ook erg leuk uit

Also verify this doesn't imply we lose the last sentence on larger encodings (can't imagine it does as the tests probably cover this, but better check).