Quick fix for errors viewing group hits when grouping on hit context.

The application would try to chop the CQL query into token parts, modify
each part, then stitch them back together. This didn't always work
right. Fortunately, BlackLab now supports top-level & operator, so we
can take a simpler approach.

For example, suppose we're searching for words starting with a 'd'
("d.*" or [word='d.*']), then grouping by hit lemma, then viewing the
group 'dog'. The old version of the application would try to create the
query [word='d.*' & lemma='dog'] wheras the new version will create the
query ([word='d.*']) & ([lemma='dog']). This approach always works
because we don't have to parse the query, we just add to it.