base class for game objects {snake, bird, mouse} and basic implementation of bird and mouse

Signed-off-by: Alexander Skjolden <alex@plastboks.net>
example firgures for bird and mouse

Signed-off-by: Alexander Skjolden <alex@plastboks.net>
testing mouse and bird on gameboard

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