Creates sets of equally spaced breakpoints for XY coordinate data.

`breaks_xy(bbox, size)`

- bbox
Numeric vector. A vector of points of the form,

`c(xmin, ymin, xmax, ymax)`

giving the outer limits of the breakpoints when expanded to nearest multiple of`size`

.- size
Numeric. The size of the cells between the breakpoints.

A list with two components:

`x`

The X dimension breakpoints.`y`

The Y dimension breakpoints.

```
breaks_xy(c(5, -45, 67, 100), 10)
#> $x
#> [1] 0 10 20 30 40 50 60 70
#>
#> $y
#> [1] -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100
#>
```