Improve Property constructors

[mjendruk]

When you create a Property with an object pointer and two method pointers, which aren't declared in the same class (e.g. in a base class), the automatical type deduction fails. So instead of Property<int>("value", object, &Class::getter, &Class::setter) you have to write Property<int, Class>("value", object, &Class::getter, &Class::setter)

[scheibel]

You could either deduct the class type using the object or using the method pointers.

Which method do you use?

[mjendruk]

This method:

template <typename Type>
template <class Object>
ValuePropertyTemplate<Type>::ValuePropertyTemplate(const std::string & name,
    Object & object, const Type & (Object::*getter_pointer)() const,
    void (Object::*setter_pointer)(const Type &))
:   ValueProperty(name)
,   m_value(new AccessorValue<Type>(object, getter_pointer, setter_pointer))
{
}