JERUSALEM - Palestinian terrorists are going after Israelis every which way they can - and recent attacks reveal they're trying out deadly new methods. When Israeli soldiers shot a Palestinian gunman in scuba gear along a northern Gaza Strip beach yesterday, they saw firsthand the terrorists' efforts to expand their arsenal beyond the standard human bomb. "They are thinking all the time, trying new methods, looking for holes in Israeli security," an Israeli intelligence source told the Daily News yesterday. In recent months, militants from both the Al Aqsa Martyrs Brigades and Hamas have been upgrading their methods and materials...