Filament guide V4 for 2020 - Black Widow

Yet another filament guide.
Inspired by http://www.thingiverse.com/thing:2030833 but
- I couldnt get that one to fit my 2020 which has a 6.2mm opening
- I wanted a slot to avoid threading

This is my V4, improvements include :
- the 45 degree angle to take the filament round the edge of the 2020
- a notch as it is rotated into the 2020 channel which locks it in a little better

V5 - I found the lock to lock it in was not tight enough, so increased it.