type mapper refactored; more stuff works for function calls

idea/testData/codegen/currentTime.jet

@@ -1,3 +1 @@
-import java.lang.*
-
 fun f() : Long { return System.currentTimeMillis(); }

idea/testData/codegen/identityHashCode.jet

@@ -0,0 +1 @@
+fun f(o: Any) : Int { return System.identityHashCode(o); }