Square tower (20-18)x20x30 mm

## Motivation
I created this simple model to compare Cura slicing in 3 different version: 15.04, 3.04 and latest 3.31 (as of May 2nd, 2018).

## What
The square tower is 20x20x30 mm with wall thick 1mm. I will post my test results with PLA filament in Monoprice Select Mini v2 3D printer.

## How
The settings of 15.04 and 3.0 comes from [MP select wiki](https://www.mpselectmini.com/slicers/cura), while the settings of 3.31 is out of box default settings with changes in lower printing te