Instead of everyone overriding save_to() and set_property() and doing
a pretty asymmetric job of implementing the various properties, let's
add a bit of structure here.
Object properties are now represented by a Core::Property. Properties
are registered with a getter and setter (optional) in constructors.
I've added some convenience macros for creating and registering
properties, but this does still feel a bit bulky. We'll have to
iterate on this and see where it goes.
Before, we had about these occurrence counts:
COPY: 13 without, 33 with
MOVE: 12 without, 28 with
Clearly, 'with' was the preferred way. However, this introduced double-semicolons
all over the place, and caused some warnings to trigger.
This patch *forces* the usage of a semi-colon when calling the macro,
by removing the semi-colon within the macro. (And thus also gets rid
of the double-semicolon.)
Add a SetInspectedObject call that tells us which Core::Object a remote
client is currently looking it. Objects get notified when they gain
their first inspector, and when they lose their last one.
Since the returned object is now owned by the callee object, we can
simply vend a ChildType&. This allows us to use "." instead of "->"
at the call site, which is quite nice. :^)
Consider the old pattern for creating a Core::Object parent and child:
auto parent = Core::Object::construct(...);
auto child = Core::Object::construct(..., parent);
The above was an artifact of the pre-reference-counting Object era.
Now that objects have less esoteric lifetime management, we can replace
the old pattern with something more expressive:
auto parent = Core::Object::construct(...);
auto child = parent->add<Core::Object>(...);
This reads a lot more naturally, and it also means we can get rid of
all the parent pointer arguments to Core::Object subclass constructors.
