Fix unicode handling and add tests

We now also return an incomplete triple to aid in debugging - non-nil
error means that this is not usable except for manual examination.
Handle comments in N-Quad documents and REPL

The parser rejects an N-Quad with a comment, so we filter those out
ahead of time. This simplifies the grammar and code generated by the
parser.
Cleanup unused vars, move unEscape and add tests
Generate parser code

ragel -Z -G2 parse.rl

ragel version 6.8 (as previously)
Run quadfix on 30kmovies.nt.gz and replace