Additional Turtle tests

Attached is a small test suite covering some of the uncovered areas of
the new spec, most notably dots and colons in pnames.

Some of the bad cases are quite similar but with the errors in different
locations, but the good tests cover important gaps.

The main missing area of coverage now is non-ASCII characters in pnames,
i.e. PN_CHARS_BASE and all the derived rules.

I wrote these with the intent that they be incorporated into the
official suite(s?), so if anyone has the power and desire to do so, feel
free.

Also available in svn at http://svn.drobilla.net/serd/trunk/tests/extra/
or browseable at http://dev.drobilla.net/browser/serd/trunk/tests/extra

-dr