easy filtering and more filters.

[asaokamei]

maybe need more filters, such as nl2br, ucwords, upper, lower, and some more for JavaScripts etc.

need to have an easy method to specify which filters to apply. some ideas...

// use some method like filter.
$data->filter('key-name', 'nl2br', 'filter2'...);

// use __call. 
$data->nl2br('key-name', 'filter2);

// set default filters for keys.
$data->setFilter('key_name', 'filter1', ...)->key_name