Smartrapcore standard - HK13 (8mm rods - 13mm walls)

update:
Oct 03: New version with a lot of improvements:
http://www.thingiverse.com/thing:1050574

Thanks for smartfriendz to share this revolution of their great design to Onshape!
We now have the source files to change the design for our needs.

Changes I made:
- adapted the parts which have rods and bearings from 6mm to 8mm size
- beefed up some parts to keep their strength with the 8mm holes
- removed the L and R signs from the parts (they are clear to me)
- changed t