Servo-powered linkage

This is both an iteration on the links in https://www.thingiverse.com/thing:2849789 along with the addition of mounts for a 9g servo. Changes to the links include:
- A two-pronged inner connector rather than a four pronged one to avoid breakages
- Adjustments to the dimensions of the connectors to make them more snug on the bearings

In order to adjust the lengths of each link, or to get models for individual links, open the links_package.scad file in OpenSCAD (http://www.openscad.org/), and change the parameters to the "servo_link," "passive_link," and "servo_horn_link" module calls at the bottom of the file (or comment one of the calls out to remove it from the model).