Wrong bbox when irregular axis is trimmed and subset bounds do not coincide with a point

[Piero Campalani]

When trimming an irregular axis, the envelope/bbox of the coverage along that axis is not correctly fit to the minimal bbox.

For instance, having an irregular axis labelled k:

   0         3    4      6
   o---------o----o------o-------> k
         [==== s =====]

 s : subset=k(2,5)
 o : grid point

The request subset [2,5] should be trimmed to [3,4] to return the minimum bbox, whereas now it is left as [2,5]. Only in the case that the upper or lower bounds fall outside the extent of the axis, the bbox is resized.

This bug slipped through because unluckily WCS systemtest n.19 trims on exact irregular k-layers.

[Piero Campalani]

Minimal bounding box applies properly to referenceable axis now after changeset:53768e7. Systemtest n.43 added.