Gridfinity Development System - Breadboard Holder

Thanks to @FruitieX for the great original model.  

Modifications from their model:

1. Resized the opening to work with the 
2. Added pass-through holes to allow wires to go under the gridfinity baseplate.
3. Removed some extra features that were left in the original Fusion file.
4. Other minor adjustments

I kept going back and forth about which would be a better version, 14mm tall + requiring adhesive removal OR 21mm tall + using the adhesive.  I ended up opting for keeping the adhesive because it makes the unit quite solid, and it is still a reasonable size.