Internationalize text strings

[Facyla]

Having the ability to easily translate the app into another language would be great for a wider use of the templates.
An easy way i'd suggest to do so is to make translation available through an indexed array (one per language), the call the corresponding translation for a given key.
E.g.:
$en = array('citadel:poi' => "CITADEL POI", 'citadel:app:title' => "CITADEL app title");
then call :
$en['citadel:poi'] to get the corresponding translation.

We can also make use of printf() for more complex templating (e.g. using variables into translations).