Grid2Polygons function has been deprecated; please use
inlmisc::Grid2Polygons instead, see inlmisc package.
GPL-2 or GPL-3. These are “copy-left” licenses. This means that anyone who distributes the code in a bundle must license the whole bundle in a GPL-compatible way. Additionally, anyone who distributes modified versions of the code (derivative works) must also make the source code available. GPL-3 is a little stricter than GPL-2, closing some older loopholes.