cpp/language/angle bracket hack

The angle bracket hack resolves a lexing ambiguity when a templated name ending in ">" is used as the template parameter of another class template or function template. Prior to C++11, when two consecutive angle brackets appeared, many lexers would interpret these as the right shift operator instead according to the language grammar. As a workaround, a space would need to be inserted between the two angle brackets so a lexer could interpret them as individual angle bracket tokens.