About antlrcpp::Any derived.

Hi,
There are the following codes:
```
class A {};
class B : public A {};
B *b = new B;
antlrcpp::Any any = b;
bool is = any.is();
```
Variable ìs' always `false'. How do I solve this type of derivation problem?

Start at the antlrcpp::Any implementation and its is() entry point, then reproduce the supplied A/B pointer example. Done means the expected behavior for checking a base-class pointer is resolved, with coverage for this derivation case.

Written by the indexing model from the issue text.