[BUG] Some field values partially or fully highlighted

[Niall Dooley]

For example field values such as the following are highlighted whereas
otherwise only the field is highlighted.

- no
- yes
- if the value contains "field" as a substring e.g. "Topsfield"
- if the value contains "int" as a substring e.g. "internet"
- if the value contains "no" as a substring e.g. "not"
- if the value contains "email" as a substring e.g. "foo@googlemail"
- if the value contains "line" as a substring e.g. "Celine"
- if the value contains "rec" as a substring e.g. "redirects"

Finally, why can't fields have no value?  It is reported as an error on
the command line.

Thanks for your time and recutils.