Allow AND operator between gml:id and other attributes when using transactions

[armin11]

We wan't to use tinyows for digitizing objects in distributed environments as an alternative for geoserver. Some of the distributed wfs featuretypes includes attributes, that defines the ids of owners of the objects and therefor we need a possibility to insert/update/delete objects by using a logical combination of the gml:id and one arbitrary other attribute. Using geoservers wf-t this is possible. I think the adoption of tinyows will be easy and help others which may have the same issue ;-) .