CharsetConverter: add charUtf32ToStrUtf8 for single utf-32 char transformation
StringUtils: add "isasciidigit", "isasciixdigit", "asciidigitvalue", "asciixdigitvalue", "isasciiuppercaseletter", "isasciilowercaseletter" and "isasciialphanum" for locale-independent ASCII operations
HTMLUtil: add "DecodeHTMLCharRefs" and helpers
Fully HTML5.0 compliant
Replace usage of HTMLUtil::ConvertHTMLToW with HTMLUtil::DecodeHTMLCharRefs
HTMLUtil: remove buggy ConvertHTMLToW