return is useless when script thorws exception
Typo fix and update docblock
Removed GetMessages from WaitforReceipt

Using this without processing them would dump messages into oblivion
Added exception on missing key
PHP Notice Fix: Removed unneeded variable.
Removed unneeded method (getMessages) from WaitforGroupId
Fixed session_start PHP notice error.
Changed Updated Status text
Very small code format change.
Update whatsapp.php demo/script after recent code changes.

Fixed getting the groups the user belongs to.
Small formatting changes.
Merge with Shiroko Master