BROOKLIN, Maine — Call it internet behind a net: Friend Memorial Public Library offers free Wi-Fi to its patrons in a tent in the library’s front yard. Situated under a large maple, the 10-by-10-foot tent has gone up in July and August for at least the past eight years to help the small library handle an influx of summer visitors in pursuit of an internet signal, said Stephanie Atwater, the library’s director. “We have a lot of summer residents and visitors both, and even people who want to be year-round take advantage of it,” Atwater said.