added a couple of helper functions to make it easier to compare values, implement Comparable and create Comparators

libraries/kdoc/src/main/kotlin/org/jetbrains/kotlin/doc/KDocConfig.kt

@@ -95,15 +95,7 @@ class KDocConfig() {
 
 protected class LongestFirstStringComparator() : Comparator<String> {
     override fun compare(s1: String?, s2: String?): Int {
-        // TODO could we make this kind of code much easier?
-        if (s1 == s2) return 0
-        if (s1 == null) return -1
-        if (s2 == null) return 1
-        var answer = s1.length() - s2.length()
-        if (answer == 0) {
-            answer = s1.compareTo(s2)
-        }
-        return answer
+        return compareBy(s1, s2, { (s: String) -> s.length() })
     }
 
     override fun equals(obj : Any?) : Boolean {