In-Progress: Connecting Carts

[eviltak]

Connect a cart with its nearest connectable cart by a joint of sorts when clicked on using the wrench.

Closes #21.

Testing

Create a world, lay down a track, add a few carts close together, and right click on one using the wrench. A joint should automatically be created between the cart clicked on and the nearest joinable cart, if a joint can be created. You can chain carts together by joining a cart with an existing joint to another cart.

Todo

• [x] Find nearest cart to join
• [x] Make joint between the carts
• [x] Update joints
• [ ] Handle joint cleanup on entity destroy
• [x] Disable collisions between connected carts

[pollend]

squashed everything and move it to another branch https://github.com/Terasology/Rails/tree/feature-connecting-carts