The new demangler is in the "swift/SIL/Demangle.{h|cpp}" files, and in the swift::Demangle namespace, which has two public entry points:
std::string demangleSymbol(llvm::StringRef mangled);
std::string demangleType(llvm::StringRef mangled);
This was necessary to support the need for LLDB to demangle Swift symbol (and type) names
Test case is included
Swift SVN r6547
