Update simplx.mirage.class.php

Added support for Request-span cache storage of Resources. Simplx_Mirage will now always use cached object instances of Simplx_Mirage_Object and  Simplx_Mirage_Class, thus also corresponding modResource, modTemplateVar and modTemplate for the duration of the HTTP Request. This means that you can use the Simplx_Mirage component with absolute minimum overhead, except for runtime RAM storage of course.