write the uppercased character to the buffer, but only returns the length of
the uppercased letter as per
http://icu.sourceforge.net/apiref/icu4c/ustring_8h.html#a50.
- Updated is_string():
If Unicode semantics is turned on, return "true" for Unicode strings only.
If Unicode semantics is turned off, return "true" for native strings only.
- Added is_binary() function that returns "true" for native strings only.
- Added first implementation of upgraded strtr function. It works except if
combining sequences or surrogates are used in the non-array method of calling
this function.
