Add $encoding input to tundra.tn.content:route, and update service
comment and README entry to reflect support for CSV, JSON, YAML, etc.
Change tundra.tn:split to use the following TN_parms returned by
the call to $service when routing split documents to TN when
$content.type.output, $encoding.output, and $schema.output are
not specified as inputs:
- TN_parms/$contentType
- TN_parms/$contentEncoding
- TN_parms/$schema