WanhaoD6_FilamentTopFeedStrainRelief

This add on fixes 3 issues with the stock feed head on a Monoprice Maker Select Ultimate or a Wanhao D6 (they are the same printer design).

1) Prevents the filament from wearing a grove in the hole the filament is fed into from the top of the printhead while it allows the filament to have a gentle turn from the spool.
I have added a picture where I use a piece of mechanics wire and hold it with screws in holes I drill in the side. The print does not have these holes yet but see picture wit