Zombicide Card Holder

##A card holder for the Zombicide board game.

**NOTE 1: Review design before using!** 12/31/2014 - As of today, I have not built this yet since I just completed the initial design yesterday. Because of this I have not had the opportunity to verify the design. Feedback is welcome

**Note 2:** The scad file has multiple attributes defined that you can change to quickly alter the design.
**1. num_slots:** This specifies the number of card slots which is currently set to 3.
**2. stack_hei