Previously setting writerStandalone = True did nothing unless
a template was provided in writerTemplate. Now a fragment
will be generated if writerTemplate is Nothing; otherwise,
the specified template will be used and standalone output
generated. [API change]
If we're producing a fragment, just skip normalization.
After all, the fragment might be somewhere in the middle
of the document. It's more important for fragments to
have consistency in rendering (so they can be pieced
together) than to normalize.
This closes#2394. It's simpler and more robust than
my earlier fix.
