More stdlib: sorting, better Appendable, other minor changes. (#245)

backend.native/tests/build.gradle

@@ -526,6 +526,11 @@ task array2(type: RunKonanTest) {
     source = "runtime/collections/array2.kt"
 }
 
+task sort0(type: RunKonanTest) {
+    goldValue = "[a, b, x]\n[-1, 0, 42, 239, 100500]\n"
+    source = "runtime/collections/sort0.kt"
+}
+
 task if_else(type: RunKonanTest) {
     source = "codegen/branching/if_else.kt"
 }

backend.native/tests/runtime/collections/sort0.kt

@@ -0,0 +1,4 @@
+fun main(a: Array<String>) {
+    println(arrayOf("x", "a", "b").sorted().toString())
+    println(intArrayOf(239, 42, -1, 100500, 0).sorted().toString());
+}