Fix column slicing behavior on recipes page

[svbarker]

Hi, long time user of the site, first time contributor! I noticed that on the recipes page, I was seeing a column ordering of 1-3-2 instead of 1-2-3, and it turned out the fix was simple so I thought I'd throw up a PR. The splice method mutates the original array, so what was happening was:

1. this.results.splice(0, split) - Remove and return the first third of the results array (column 1)
2. this.results.splice(split, split + split) - Remove and return the back half of what remains of the results array (what should have been column 3)
3. this.results.splice(-split) - this.results is now split items long, so take remove and return all of the rest of it (what should have been column 2)

I switched these to slice, which shallow-copies instead of mutating the original array, which I think is what was intended in the first place.