Fix crash when ship hits map boundary (fixes #234)
Fix crash when ship hits map boundary (fixes #234)

lanyudhy/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,lanyudhy/Halite-II,lanyudhy/Halite-II,lanyudhy/Halite-II,lanyudhy/Halite-II,lanyudhy/Halite-II,lanyudhy/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,lanyudhy/Halite-II,lanyudhy/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,lanyudhy/Halite-II,lanyudhy/Halite-II