Tiny Flex Extruder Reloaded

I really like the simplistic design of the the Tiny Flex Extruder. Sadly it
- didn't fit my e3Dv6. I want the extruder to be a unit including the hotend for easy replacement/ exchange
- uses only one screw to carry the idler lever which makes it prone to bending
- doesn't have adjustable idler pressure and a quick release.

This design adds a quick release, adjustable spring pretension and a quick release as well as a clamp for any groove-mount hotend. Use your own clamp to attach the extr