gml:GridEnvelope upper-corner has minimum value to 0 when subsets are requested

[Piero Campalani]

When making WCS a request with subsets on a coverage the upper-corner (gml:high) of the gml:GridEnvelope in the gml:domainSet of a WCS response trims to 0 the values in case the upper value is negative.

For instance, having a cube with 3rd dimension shifted in its entirety on the negative indexes:

$ rasql -q "select sdom(c) from MODIS_35U AS c" --out string
...
Result element 1: [0:446,0:646,-3:-2]

would return the following GridEnvelope:

<GridEnvelope>
  <low>0 0 -3</low>
  <high>10 20 0</high>
</GridEnvelope>

upon a WCS request with some subset (that hence require to call the setBounds WCS function in wcs2.extensions.AbstractFormatExtension.java).