Anet A8 X-Idler set with tensioner

Another version of X-idler for ANET A8 with integrated tensioner and brackets for M3 nuts.

other upgrades currently installed on my printer:

- Stiff Y- front plate with integrated tensioner:
https://www.thingiverse.com/thing:2867409

- E3D carriage:
https://www.thingiverse.com/thing:2278021

- simple spool holder:
https://www.thingiverse.com/thing:2257054

- z-antiwobble bracket
https://www.thingiverse.com/thing:2870504

- optional Z limit switch:
https://www.thingiverse.co