Add automatic layer height detection

[iitggithub]

Currently, the layer height needs to be passed to the script via a command line parameter. In prusa slicer, I would need to have the post processing script set to the following on my mac:

"/Library/Frameworks/Python.framework/Versions/Current/bin/python3" "/Users/stutaki/iitggithub/Bricklayers/bricklayers.py" -layerHeight 0.2;

The script should use the G-code comments to determine the layer height the model was sliced at.

During testing i found that Prusa printers seem to mention the layer height like so:

; layer_height = 0.15

and from some digging around online, I believe Bambu Labs uses:

; Z_HEIGHT: 0.15

[iitggithub]

Submitted Pull request #26 to add automatic layer height detection via G-code comments

[taotien]

According to https://help.prusa3d.com/article/post-processing-scripts_283913, you can also base it off of an environment variable. I'm assuming it's gonna be SLIC3R_LAYER_HEIGHT.

Although, it might be more convenient to just detect from the file for users running post-processing manually.

[iitggithub]

According to https://help.prusa3d.com/article/post-processing-scripts_283913, you can also base it off of an environment variable. I'm assuming it's gonna be SLIC3R_LAYER_HEIGHT.

Although, it might be more convenient to just detect from the file for users running post-processing manually.

I've pushed a commit that will try to obtain the layer height from the SLIC3R_LAYER_HEIGHT environment variable. If that fails, it'll try to find the layer height from the G-code comments and if that fails, it'll use the command line argument -layerHeight. Even if -layerHeight isn't specified it does set a default value of 0.2mm so we should be safe and it covers those users who want to run it manually.

I've also added a regex to support Simplify 3D G-code layerHeight comments.