Implement WCS-T Update

[Vlad Merticariu]

Implement the update operation in the WCS-T extension, allowing coverages' values to be changed, as well as allowing coverages' domains to be extended.

Besides the request parameters defined in the WCS-T specs, the following vendor specific request parameters are available:

InsertCoverage request:

• pixelDataType: if cell values are given as tupleList, the cell data type can be specified through this parameter, as one of the data types that GDAL supports. Default: Byte.
• tiling: indicates the tiling strategy of the array holding the coverage's cell values. The language indicated at ​http://www.rasdaman.org/wiki/Tiling must be used.

[Peter Baumann]

• can we close this?

This documentation snippet above should be made available in the general WCS-T documentation, if not there yet.