Add an attribute to deactivate by default some controls in the form

[mike]

With jForms 1.1 beta we can do in a controller something like that :

$form->deactivate('nom_du_control', true or false);

But it could be useful to do such a thing directly in the xml form file. For example:

<input ref="date_naissance" type="date" deactivate="true">
    <label locale="mymodule~date.naissance"/>
</input>

In this way we don't have to deactivate a control everytime if we want to use it only once. This could work on every controls including group and choice, like we can do with the method.