smarty custom functions namespaces

Hi,

I've added a crude form of namespaces to my private copy of Smarty.  A
template function like:

{namespace:test}

...causes the test() function in the smarty_function_namespace class to
be called.

I'm planning to use this feature in TikiWiki to provide accessor-like
template functions to access various data: article::title,
article::description and so on.  I though that this might be of more
general use, so here is a patch for this morning's CVS snapshot of Smarty.

-- 
Michael