XMLs of LHCb properly read

1) Added XML declaration parsing, for example <?xml version="1.0" encoding="ISO-8859-1"?>
2) Added possibility to declare a field with the "member" name. The treatment is identical.
Parse successfully *all* CMS and LHCb selection xmls
Do not store the rootmap attribute in TClass
Implement transient members via the "persistent" attribute

Found in CMS selections.