Update xml parser to accept castxml output

Update xml parser to accept castxml output

Update the function and argument annotations from gccxml to castxml
style since castxml does not support 'gccxml' attributes and only
supports user defined string attributes through using the 'annotation'
attribute.

Update nested namespace parsing since castxml does not provide the
'demangle' attribute which provides the entire expanded declaration
of a type. The solution is concatenating the namespaces recursively.