Implement AutoPacket::Call

[codemercenary]

This feature allows a user holding an AutoPacket to manually delegate control to another routine using AutoPacket::Call.

void MyClass::AutoFilter(AutoPacket& packet) {
  Decoration<1> myOutputValue;
  packet->Call(
    [&] (const Decoration<0>& in, Decoration<1>& out) {
      assert(&out == &myOutputValue);
      out.i = 100;
    },
    myOutputValue
  );
}

Assuming that p is decorated with Decoration<0>, the above causes the lambda function to be called with the parameters mapped correctly, and the output value is captured and stored in myOutputValue.

This process is efficient in that it doesn't create ANY copies of myOutputValue.

• Support function object calls
• Support dumb function calls
• Be efficient! Outputs by value should not be copied