SES-1839 Don't render "error" span when there is no error message.
Merged in dvisser/sesame/ses-1839 (pull request #139)

SES-1839 Don't render "error" span when there is no error message.
Preserve whitespace when parsing sparql-results+xml
Preserve whitespace when parsing transaction XML
SES-1844 : Add queryresultio tests for literals

New literal tests include whitespace, newline, double quotes and single quotes
SES-1844 : Add more tests for tuple results roundtripping

Some of the tests fail in the TSV parser, that seems to be a little lax
with the way it calculates positions so it does not smoothly roundtrip
for new line characters, tab characters, and bindings that start with
double-quotes and have no datatype. 

Might be useful to convert it to using a third-party TSV parser. For
now, the failing tests are commented out.
Merged in SES-1844 (pull request #140)

Preserve literal whitespace in sparql-results+xml and transaction xml