New Turtle LITERAL* test inconsistencies

The new LITERAL* tests added to the Turtle test suite are inconsistent
with the other tests in two ways:

1) Escapes are written in lower case, e.g. \u000b instead of \u000B

2) In some output files, characters are escaped where there is no need
to escape, so implementations are unlikely to produce such a file

3) In literal1_all_punctuation.nt, quote is escaped as \u0022, but \" is
allowable in ntriples and is used in several other test outputs.

Attached is a diff fixing these issues.  As with my previous patches,
they should be identical triple-wise and not break anything capable of
passing the old high-level suite, but make it possible for
implementations to pass based on exact byte-level comparison.

-dr