Retraction Temp, Length and Speed towers.

I was having some trouble dialing in the retraction on PETG, so I used some towers based on m1ngr's design to test effects of temp, retraction length and speed.

I simplified the object a bit, sharp corners and made it a single solid - I printed with 3 perimeters,3 bottoms layers, no top, no infill. Of course I made it so there are 2 of the towers.

**You need to have firmware retraction enabled for this to work!**

There are three versions of the python script - one for each setting. I w