fix 2.0.11 changes
Added raptor_new_term_from_counted_string to write a term as N-Triples

(raptor_new_term_from_counted_string): Added

(raptor_term_to_turtle_counted_string, raptor_term_to_turtle_string):
Added references to new function and N-Triples versions below.

(raptor_term_to_counted_string, raptor_term_to_string): Added
reference to new function and Turtle versions above.