Inner classes (#207)

* Inner classes lowering

* cmd line fix

* tests

* * reverted adding parameter to inner classes constructors
* variables are identified by their descriptors

* review fixes

backend.native/tests/codegen/innerClass/getOuterVal.kt

@@ -0,0 +1,12 @@
+class Outer(val s: String) {
+    inner class Inner {
+        fun box() = s
+    }
+}
+
+fun box() = Outer("OK").Inner().box()
+
+fun main(args: Array<String>)
+{
+    println(box())
+}