Call this function to register request handlers, including functions,
callable objects and events. New plugins can be added that support
additional registration methods and request processors.
Parameters:
$sType - (string): Type of request handler being registered; standard
options include:
XAJAX_FUNCTION: a function declared at global scope.
XAJAX_CALLABLE_OBJECT: an object who's methods are to be registered.
XAJAX_EVENT: an event which will cause zero or more event handlers
to be called.
XAJAX_EVENT_HANDLER: register an event handler function.
$sFunction || $objObject || $sEvent - (mixed):
when registering a function, this is the name of the function
when registering a callable object, this is the object being registered
when registering an event or event handler, this is the name of the event
$sIncludeFile || $aCallOptions || $sEventHandler
when registering a function, this is the (optional) include file.
when registering a callable object, this is an (optional) array
of call options for the functions being registered.
when registering an event handler, this is the name of the function.