Optimized Parametric Lego Duplo Brick

This is a remix of https://www.thingiverse.com/thing:1778

* re-measured for better connection and easier separation
* nibbles on top side slightly beveled for better snap-fit experience

Instructions are the same as for the original work:
* print a small brick
* try if it works for you
* if needed: make small changes within the openSCAD file, re-export your desired brick sizes with your updated settings
* print and try again

If you come up with an even better version feel free to share :-)