XBMCTinyXML: detect XML charset and convert data if needed
XBMCTinyXML: add 'GetXxCharset' functions
Remove hacks and workarounds for XML encoding
XMLUtils: remove not needed anymore and semi broken 'HasUTF8Declaration' and 'GetEncoding'
* 'HasUTF8Declaration' can't really detect declaration with whitespaces and can false detect encoding beyond declaration end
* 'GetEncoding' works only if XML is stored in singlebyte encoding