Ship parts

Howdy, trying to make use of branches, not sure If I got it right.
I have finished with this branch, now the next thing to do is a pull request right?

Removed ship sprites and replaced them with procedural shapes...
In general it’s best to avoid returning _mutable_ types. Instead, you’d use a return type of `CGPathRef` (which is just like `CGMutablePathRef` except whatever is calling this can’t just add random stuff to it for no reason—they’d have to copy it first). You won’t have to change anything in how the method is implemented, just the return type.