Base class serialization and QOL features

With this release I covered some more use cases, namely the serialization of base classes and I added some convience features.

struct Object : public Point
{
    int idx = 0;
    DEFINE_SERIALIZABLE(Object, tser::base<Point>(this), idx)
}

The first convience feature is being able to directly initialize a BinaryArchive<T>(t) with an object.
The second one to a load an object directly in one line using auto t = tser::load<T>("base64EncodedString") .

Furthermore the tests for the base64encoding were improved and now cover all possible input values.