provide copy contructor and operator = for lexical_feedback class. * lex.h, lex.ll (lexical_feedback::lexical_feedback): Provide copy constructor. Correctly initialize looking_at_anon_fcn_args to false. (lexical_feedback::operator=): New function. (lexical_feedback::init): Simplify. (reset_parser): Assign new lexical_feedback object to global lexer_flags instead of calling init on existing object.