More Minecart Improvements to the Java Snapshot

The Following are minecart features that would add on to the current snapshot.

• Speed Rails. They would be made of copper they would be able to change the max speed of the minecart. You would power it with a Redstone strength it would change the speed of the cart 2X the strength. The upgraded speed is only a game rule right now.
• Furnace minecarts should be faster. They should be faster then other cheaper methods.
• You should be able to chain minecart so they can become trains or help them not all hit each other.