This rev. add a 'set' and 'delete' static functions to the Observer.
They allow to set or delete (only for objects) properties on
observed objects or arrays.
With this, the 'set' functions in Store and Component are no longer
necessary, so they have been removed.
Closes#138
Some people apparently believe that the framework should magically
solves all problems from the programmers, shielding him from thinking.
It is not possible, and maybe a bad idea, because it will only delay the
inevitable... If one does weird stuff without knowing what is going on,
someone will get hurt.
However, in this specific case, something can be done.
closes#104
Géry Debongnie