Mounting plate for MKS Gen L V1.0

Mounting plate on which MKS Gen L V1.0 controller board can be mounted. Plate can be attached to whereever needed.

Code includes screw threads and thumbscrew module, i tested those but they weren't practical in this case.

MKS board specifications:
https://github.com/makerbase-mks/MKS-GEN_L/tree/master/hardware

Code uses OpenSCAD threads module from Dan Kirshner:
https://www.thingiverse.com/thing:1938150