Name lookup

If you prefix a unique name with * or ?, this will do a name lookup, looking for the entity. This only works inside a comment associated with an entity, not in template files etc.

It does a similar search to the actual name lookup in C++: It starts at the associated entity and appends its scope to the partial unique name given, going to the next higher entity if no matching entity can be found, etc.

For example:

```cpp /// a. struct a {};

namespace ns { /// ns::a. struct a {};

/// [This will link to ::a, no lookup here](standardese://a/).
/// [This will link to ns::a](standardese://*a/).
void foo();

/// b
template <typename T>
struct b
{
    /// c.
    void c();

    /// [This will link to ns::b<T>::c()](standardese://*c/).
    void foo();
};

} `