Function mlb_unescaped 

fn mlb_unescaped<'i>(stream: &mut &'i str) -> &'i str

mlb-unescaped extended with mlb-quotes and LF

This is a specialization of basic_unescaped to help with multi-line basic strings

warning: newline is not validated

ml-basic-body = *mlb-content *( mlb-quotes 1*mlb-content ) [ mlb-quotes ]

mlb-content = basic-cha / newline / mlb-escaped-nl
mlb-quotes = 1*2quotation-mark