Those characters were treated as invalid characters.
UTF8ToInt_FirstOctet incorrectly checked if the first octed is zero (after removing first bits).
This is a case only if the utf-8 character consists of two bytes. For 3 or 4 bytes
the first part can have all bits equal zero.
- utf8 auxiliary functions moved to utf8_private.h file
- in utf8.h are shown only functions available for consumers
- template functions has been moved to utf8_template.h (in utf8.h are only declarations)
utf8_template.h is included at the end of utf8.h
- functions which take std::ostream changed to template (the stream is a template argument now)