CTC Aluminiumtisch 3-Punkt Lagerung V2, 3-point levelling for CTC V2

Remix of https://www.thingiverse.com/thing:1833104 by xxricsxx with 3-point levelling of the heatbed from CBiker (https://www.thingiverse.com/thing:746345)

[UPDATED VERSION ]

back_V2.stl - fixing of the back screws no longer dependent on legth of cross profiles.

Other parts used:

- 2x Cap_20x20.stl
- all parts from https://www.thingiverse.com/thing:1833104 by xxricsxx
- Druckbett_3Punkt_Leveling_1.stl (https://www.thingiverse.com/thing:746345/#files) by CBiker
- adjustable Z-En