Move functionality into traits about hex_math

[leftiness]

Or maybe instead of putting it on point, it should go on like HasValues since HasValues is what makes a struct interoperable with my functions. Or it could be a function like _.chain. chain(point).travel(5, east).distance(otherPoint);

[leftiness]

If I can make this happen, it'll really clean up a lot of code. It would let me chain simple transforms together, and I think it would even be possible to do into()/etc:

Point(1, 2, 5)
  .travel(Direction::East, 1)
  .rotate(Point(0, 0, 0), 1)
  .line_through(Point(1, 1, 1), 3);

Maybe it's too complicated, but a lazy evaluated version would be sick.

[leftiness]

Basically, travel() should be in a trait. Travel::travel(&self, Direction, distance: i32). impl<T, U> Travel<U> for T where T: Borrow<Point<U>>. Then I can self.borrow() to get an &Point which I can use to return a Point.

Apply the same concept to all of those functions. Distance, etc.

Then I'll be able to do my_point.travel().rotate().etc().

[leftiness]

Remember to do point.direction(other) instead of Direction::from((point, other)). See #93.

[leftiness]

Merged