Customizable Temperature Tower Version 2

[2018-03-28] User *i_has_it* found out that the only thing to make it work with **S3D** is to adapt the layer change script like that:

;LAYER:[current_layer]

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[2018-01-25] Thanks to user *groenewaldd's* hints in the comments i have adapted the script to work for **slic3r** *and* **Cura**.

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This is practically a remix of https://www.thingiverse.com/thing:2614204.
The difference is that it has an overhang on the right side with a pointy cone on top of it. This is supposed to show how exact your printer prints (and cools) small pointy details.
You also can change the direction of where the highest and the lowest temperature will print: on top or on the bottom of the tower.

### Usage example in Slic3r:
- - -

#### 1. Generate the tower with openscad:
$ openscad tempTower.scad
Set the following variables in the openscad window to your liking:

// temperature of the first lowest block
start_temp = 220;
// temperature of the last highest block
end_temp = 185;
// change in temperature between successively printed blocks
temp_step = 5;

Render and export the model to .stl and close openscad.

#### 2. Generate gcode with Slic3r:
1. Open the .stl file in Slic3r.
2. Set layer height to 0.2mm. If not, multiply the skip and block parameters by (0.2mm/new_layer_height).
2. Add the following to:
"Printer Settings" -> "Custom G-code" -> "Before layer change…