Adjustable Support for Plastic models (M10 mod)

Minor changes to alo635 's original design:
- added 10 mm hole in the base for mounting
- added teeth to all the supports to give rubber bands a better grip
- arrow symbol embossed instead of protruding

Print 2x:
- support_FnB.stl
- arm_LR
- arm_FB

Unchanged parts, just renamed:
- bras_cote_cor.stl -> arm_LR
- bras_de_cor.stl -> arm_FB

EDIT:
- added knob_m10.stl - use infill mod to insert a m10 nut in slicer settings