lookup() searches for symbols in the given binding and the enclosing scopes,
while find() searches for symbols only in the given binding.

Done with: erikv

This reverts commit f4163b8b.

doing it in 1.3 as well to avoid possible later conflicts

For example std::string, which is a typedef of std::basic_string.

Reviewed-by: Thorbjørn Lindeijer <thorbjorn.lindeijer@nokia.com>

Now, the ASTVisitor constructor takes a valid reference to a TranslationUnit.