Extent-object

[wkearn]

From @wschwanghart in TopoToolbox/topotoolbox#5

Inspired by R-raster packages, I suggest to introduce a new numeric class storing spatial extents. These can be used to clip and crop rasters and STREAMobjs, and to set display extents of axes (see setextent, getextent, padextent,...).

[wschwanghart]

An extent object could also be simply adopted from MATLAB's Mapping Toolbox function aoiquad. The function is new in R2025a.