more class and method signatures, use writer wrapper

(not yet complete)

own writer will be used to write both java and kotlin signatures

compiler/testData/compileJavaAgainstKotlin/method/QExtendsString.java

@@ -0,0 +1,8 @@
+
+class Question {
+    // id2 is to prevent java type parameter type inference
+    static <T> T id2(T p) { return p; }
+    {
+        String s = id2(namespace.id((jet.typeinfo.TypeInfo) null, null));
+    }
+}