M25-at-layer-postprocessor for Slic3r

M25-at-layer-postprocessor
The .sh gets invoked from the slic3r post-processing scripts field.
The .pl is invoked as a terminal (so you can type into it) by the .sh
Just put them both in the same folder and invoke the .sh from Slic3r.

- In slic3r's preview, determine at what Z value heights you need an M25 pause, to insert nuts or whatever, and remember those digits.
- Export the file to gcode, or send to octoprint, and the post porocessing script will kick in, offering you a terminal to enter the Z values.
- Enter them separated by carriage returns (hit enter), then hit enter by itself to finish.
- If nothing failed you will now have a gcode file that has M25 pauses inserted as instructed.

Be aware that I use Octoprint's event handlers to add the necessary wrangling after the pause, and before the print resumes. (Hence the octoprint gcode screenshot). Failure to do these things usually means a failed print if (when) you bump the bed during the pause.
You could actually w