Add CHANGES entry and regression test for #676

Examples/test-suite/go/class_case_runme.go

@@ -0,0 +1,12 @@
+package main
+
+import . "swigtests/class_case"
+
+func main() {
+	b2 := NewClassB2()
+	// This used to fail with:
+	// panic: interface conversion: interface {} is class_case.SwigcptrClassB2, not int
+	if Test2(b2) != 1 {
+		panic("Unexpected overload used")
+	}
+}