Add items (aka CLEAR_ACTIVE_SPOOL) to START_PRINT and END_PRINT

[tkunchick]

Firstly, thank you so much for sharing these macros. I use them all the time on my E3v2Neo.

I am not much of a programer, so it takes me a bit to wrap my head around what things are doing, but you have provided a lot of documentation and I am able to putter through.

I recently started using SPOOLMAN to track my spools. I have my slicer filament gcode to select the spool id and clear in the start/stop gcode, but I noticed that on a canceled print, the spools were not cleared.

[gcode_macro PRINT_END]
rename_existing: KM_PRINT_END
gcode:

  # Put macro code here to run before PRINT_START.

  KM_PRINT_END {rawparams}
  CLEAR_ACTIVE_SPOOL

  # Put macro code here to run after PRINT_START but before the print gcode

is this the best way to add the clear active spool?

it seems to work, just want to make sure I wasn't fiddling something else up.