3D Printer 3xLM8UU Minimal X Carriage (with symmetric/balanced tensioning mechanism) [#SCOUTcorexy design]

####Update: I have managed to re-do the X carriage to re-gain the lost bearing due to space constraints. Rather than updating this Thing I'll leave it as is and create a new thing altogether to reflect the new design. Here's the link: http://www.thingiverse.com/thing:1566017

Update: Added a Smartrapcore-compatible 30mm distance between belts STL, as requested on reprap forums. It is still compatible with the DualHotends Mount that I develop for SCOUTcorexy (https://www.thingiverse.com/thing:1