rewrite oneofakind with map since we're starting to see longer arrays

fun.go

@@ -538,18 +538,17 @@ func firstclass(honk *Honk) bool {
 }
 
 func oneofakind(a []string) []string {
-	var x []string
+	seen := make(map[string]bool)
-	for n, s := range a {
+	seen[""] = true
-		if s != "" {
+	j := 0
-			x = append(x, s)
+	for _, s := range a {
-			for i := n + 1; i < len(a); i++ {
+		if !seen[s] {
-				if a[i] == s {
+			seen[s] = true
-					a[i] = ""
+			a[j] = s
-				}
+			j++
-			}
 		}
 	}
-	return x
+	return a[:j]
 }
 
 var ziggies = make(map[string]*rsa.PrivateKey)