LocalizationGridTransform2D should defines a WarpGrid

This is a speed improvement task: LocalizationGridTransform2D should extends WarpTransform2D and constructs a javax.media.jai.WarpGrid the first time its getWarp() method is invoked. It will allows the GridCoverage "Resample" operation to use a JAI's Warp implementation instead of Geotools's one, which give the opportunity for more optimization on JAI's side.