Servo wheel 4.0 (Q66639)

This is a new version of the parameterized Servo wheel for mobile robots: http://www.thingiverse.com/thing:9071 These are the wheels used by many printbots such as Miniskybot or Scout. The improvements of the Version 4.0 are: * Adaptation to the 3 types of Futaba 3003 servo horns: rounded, 4-arms and 6-arms * New drills for attaching the horns. Now it is easier to screew the horns to the wheels The sources are stored in the Miniskybot 2 github: https://github.com/Obijuan/Miniskybot/