[stdstring] get rid of CStdString in LocalizeStrings, LangInfo, LangCodeExpander

NOTE: settings values are compared case-sensitive in SettingOptionsRegionFiller
[stdstring] get rid of CStdString in CCurlFile's http get/post functions
[stdstring] get rid of CStdString in CGUIControlFactory::GetConditionalVisibility
[stdstring] get rid of CStdString in CGUIKeyboardFactory, CGUIWindow::OnEditChanged
[stdstring] get rid of CStdString in CGUIListItem, CFileItem, CFileItemList
[stdstring] get rid of CStdString in xbmc/URL
[stdstring] get rid of CStdString in GUIMediaWindow, and overridden functions in children
[stdstring] get rid of CStdString in IGUIContainer, IGUIControl and implementations
[curl/URL] Compare URL protocol options for CurlFile in lower-case.