Bring in new TUT library build. Clean up ensure_equals() overloads.

The new TUT library build eliminates the ambiguity about ensure_equals(const
char*, ...) versus ensure_equals(const std::string&, ...). Now it's all based
on const std::string&. Remove pointless const char* overloads and ambiguous
forwarding templates.
With clang in Xcode 6, any new datatypes we intend to use with ensure_equals()
must have operator<<(std::ostream&, datatype) declared BEFORE lltut.h
#includes tut.hpp. Reorder code in certain test source files to guarantee that
visibility.