moved snake eat method out of the Snake class and let GamePlay class handle snake operation upon eating

Signed-off-by: Alexander Skjolden <alex@plastboks.net>
added lock mechanism for locking the linkedlist when modifying it and snake eat operations

Signed-off-by: Alexander Skjolden <alex@plastboks.net>
only draw food if the linkedlist is not locked

Signed-off-by: Alexander Skjolden <alex@plastboks.net>
getter method for gameplay object

Signed-off-by: Alexander Skjolden <alex@plastboks.net>