Flexible filament adapter for Mk8 dual extruder

This is a remix of the flexible filament adapter by rcairbum. It's changed to fit the geeetech mk8 dual extruder. This prevents flexible filament from collapsing after the cog wheel. You may need to make the holes a little bit bigger after printing, to fit the barrel exactly. Also, you have to make sure the filament can flow freely. Printing too close to the print bed can cause the filament to collaps still.