List object properties

[unsegnor]

Examples:
Get an existing object from the repository
do object.listProperties()
then I should get a list of the properties that have been setted for this object

Rules:
I would like to get the list of properties for every object.
I would like to also use the property 'properties' of the object and any other to store my own values.

Doubts:
Write any situation that may be not so clear and you think that we need to work on.

Developer Notes:
We could mainain a list of properties as an special property in the object, like the ID so that we could get the properties on every moment for that specific instance.