T_PAAMAYIM_NEKUDOTAYIM is the double colon scope resolution thingy PHP uses – ::
Quick glance at your code, I think this line:
return $cnf::getConfig($key);
should be
return $cnf->getConfig($key);
The first is the way to call a method statically – this code would be valid if $cnf contained a string that was also a valid class. The -> syntax is for calling a method on an instance of a class/object.
