Public Television writers repped by Writers Guild of America have unanimously ratified a new four-year contract. Deal covers writers who script content for the three major producers of public TV programming, WGBH, WNET and KCET, plus smaller companies that generate content for PBS. Made-for-internet programming is covered for the first time, in this deal, which calls for 2% rate increases in the second year, and 2.75% in the third and fourth years.