- Same code as in {sp} for `type="regular"`
- Set `offset` as random for a random starting point.
- Drop units of `l` necessary for `type="regular"`, otherwise units problem in `grp`. It may be necessary to add `@importFrom units drop_units`
- If only a unique "size" is fixed, then sample will be regular over all. This means one point every x meter. I guess this is similar to `type = random` where not the same number of points are sampled on each line. Can maybe add some information about this in the doc.