Optionally sort features sent using layerSpecificExport

[MattiasSp]

Description
When using layerSpecificExport to e g send features to the OrigoServer excel creator, it would be nice if the resulting excel file could have features sorted alphabetically.

Proposed solution
I feel it would be most flexible to keep the OrigoServer excel creator ordering its output according to the input, and let the clients send data in the order they want. So adding a configuration parameter sortColumn to the POST_JSON method of the layerSpecific export and have features sorted before they are sent would be a good improvement.

Alternatives considered
Sorting in the backend service, in this case OrigoServer's excel creator. Although, that would only solve the issue when using that specific service. And to keep it optional, it would still require a change in the client to send parameters specifying whether to sort, what column to use, descending or ascending etc.

[steff-o]

Heads up! Easy as it may seem, even this can become complex as you would have to take locale settings into considerations or not, depending on the user's needs.