Adding `Seq.contains`
Greatly simplifying the code for `in-radius`

You'll notice that I also changed the test to sort the lists of `who`
numbers.  This is because the code for `in-radius` in JVM NetLogo is
_even more_ long-winded and insane, and results in getting the `who`
numbers in a different order than my new code here does.  Since I'm not
inclined to spend my time on tearing up an age-old file that does in 101
lines of Java what I do here in 6 lines of JS, I figure, if you can't
beat the game, change the rules.