FDM Friendly "Steins;gate" Upa

I found myself using spope's Upa as a benchmark print, but it required a lot of modification to actually get it to print in one part. Even as multiple parts, it's still not designed to be printed by an FDM printer.

I decided to start from scratch and make my own model, and this is what I came up with. It's not perfect, and I learned a lot in the process about modeling features onto a sphere. There re a few goals I was going for when designing the model:

- Make no ugly unprintable curves (meaning have the bottom of spheres not have an unprintable overhang without support). The underside of the ears have a 30 degree overhang (which wasn't a problem for me even with the not-so-great part cooling fan on the Printrbot Play) and the underside of the body has a 45 degree overhang, so that should print perfectly for anyone.

- Don't have a bunch of intersecting shells that make it impossible to print in one piece. This is a freebie with fusion.

- Do some stress-testing.

- Make i