[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}}
[ADD] Simplified array_push notation
[ADD] EchoStatement without '(' and ')'

#18 and #12
[ADD] ReturnStatement without '(' and ')'

#18
Fix #8
[ADD] statements without '(' and ')'

include, include_​once, require, require_​once without '(' and ')'
Revert "ugly fix for echo "something" instead echo(something)"

This reverts commit 423b80bc44aff2ba4496231dbc4775ed1cecc4c5.
Merge https://github.com/btwael/mammouth into my-fixes