Add more console operations, nicer naming in natives. (#46)

backend.native/tests/runtime/basic/hello0.kt

@@ -1,4 +1,3 @@
-// TODO: remove kotlin_native.io once overrides are in place.
 fun main(args : Array<String>) {
-  kotlin.io.print("Hello, world!")
+  println("Hello, world!")
 }

backend.native/tests/runtime/basic/hello1.kt

@@ -1,4 +1,4 @@
 // TODO: remove kotlin_native.io once overrides are in place.
 fun main(args : Array<String>) {
-  kotlin.io.print(kotlin.io.readLine())
+  print(readLine())
 }

backend.native/tests/runtime/basic/hello3.kt

@@ -0,0 +1,3 @@
+fun main(args : Array<String>) {
+    print(239)
+}