Those methods return true if the val character was escaped and put
to the out stream. If the character is invalid for such a stream
they only return true without putting it to the stream.
A wide string was first changed to utf-8 and then escaped to json/xml/csv
which is incorrect. First should be escaped and then changed to utf-8.
Add TextStreamBase<>::iterator and TextStreamBase<>::const_interator as classes
with a method wchar_t get_unicode_and_advance(const iterator & end)
to return one character either from utf-8 stream or from wide stream.
Let TextStreamBase<>::operator<<(wchar_t v) correctly use utf-8.
Tomasz Sowa