Anet A8 Bear Upgrade

This is another rigid frame to replace Anet A8 stock acrylic frame.

This frame was originally designed by [pekcitron-thingiverse](https://www.thingiverse.com/pekcitron) / [gregsaun (github)](https://github.com/gregsaun) for the Prusa i3 MK2, MK2s, MK2.5 and MK3.

I like the design so much and decided to make it available for Anet A8 as well.

All printed parts from the original [Prusa i3 Bear Upgrade v2.0](https://www.thingiverse.com/thing:2808408) can be used on this Anet A8 Bear Upgrade version.

The only things that have been added is the X,Y,Z endstop switch mount, trapezoidal nut adapter and Y belt holder.

Of course, the dimensions / length of the aluminium extrusion will be different from the original as well.

This conversion will use stock parts from the Anet A8. Bill of Materials will be updated soon.