telling next segment to move up/down

after the current segment moves up/down it needs to let the next one do
that.  I also uncommented the code in collidesWith() to let the
centipede know that it ought to change its direction if it collides
while moving up/down.
Merge branch 'master' of https://github.com/mikewideman/441Concurrent

Conflicts:
	src/game/Centipede.java