[ADD] ? as isset() - part2

example:
http://mammouth.wamalaka.com/#try:{{%0Aif%28_GET[%27lista%27]%3F%29%0A%20%20%20%20echo%28%27list%20isset%20!%27%29%0Aif%28obj.field%3F%29%0A%20%20%20%20echo%28%27field%20isset%20!%27%29%0Afield%20%3D%20%27someField%27%0Aif%28obj{field}%3F%29%0A%20%20%20%20echo%28%27list%20isset%20!%27%29%20%20%0Aif%28%40field%3F%29%0A%20%20%20%20echo%28%27field%20isset%20!%27%29%0A}}