Add "hidden" columns/fields into dbObject

[Skazza94]

In current version, every column of a table mapped into a dbObject is accessible through the magic getter method and editable through magic setter method.

But sometimes it's important to hide some fields/columns from the model (for example, access user password with $user->password is not that good, as updating it with $user->password = "random").

I've added a $hidden array, that holds column names that can't be accessed with magic methods. This array must be declared into the model class, as the other arrays supported by the library.

class User extends dbObject {
    protected $dbFields = array(
        'username' => array('text', 'required'),
        'password' => array('text', 'required'),
        'is_admin' => array('bool'),
        'token' => array('text')
    );

    protected $hidden = array(
        'password', 'token'
    );
}

If you try to:

echo $user->password;
echo $user->token;

Will return null, and also:

$user->password = "my-new-password";

Won't change the current "password" value.

[avbdr]

thats a good pull request. Can you please add new feature description in a readme?

[Skazza94]

@avbdr Done, check it out! :)