LiveTable generator does not escape XWiki syntax in JSON strings.

The JSON code is generated from a page in syntax XWiki/2.0 with target syntax plain. Typically a field is generated as such:

           "$escapetool.javascript(${colname})" : "$escapetool.javascript(${text})"

Any wikitext in the result of the expression $escapetool.javascript(${text}) will be rendered to plain syntax. In particular '(((' and ')))' are problematic as these will be rendered as verbatim new line characters, which results in unparsable json code.