Start getting superclass constructors working.

This also means the metaclass inheritance hierarchy parallels
the regular inheritance chain so that the subclass can find
the superclass constructor.

test/constructor/superclass.wren

@@ -0,0 +1,25 @@
+class A {
+  this new(arg) {
+    io.write("A.new " + arg)
+  }
+}
+
+class B is A {
+  this otherName(arg1, arg2) super.new(arg2) {
+    io.write("B.otherName " + arg1)
+  }
+}
+
+class C is B {
+  this create super.otherName("one", "two") {
+    io.write("C.create")
+  }
+}
+
+var c = C.create
+// expect: A.new two
+// expect: B.otherName one
+// expect: C.create
+io.write(c is A) // expect: true
+io.write(c is B) // expect: true
+io.write(c is C) // expect: true