Folger Tech Sliders and Carriage Remix V2

**Rev17 Slider for M6 Wheel Screws**
As per a request I added a slider to use M6 holes for the wheels instead of the M5 holes.
The STL files & openscad files for those have M6_ as the prefix of the names.

**Rev23 Carriage**
I had to add a little more access room for Right Rod Locknut.

I am changing the original hotend to the e3d Lite6, so since I have to re calibrate it anyway, thought I would change the carriage & sliders while I was at it. This is a remix of my previous remix. http:/