Clean Blender text logs before file saving

Слиты nikitronn запросил слияние clean_internal_buffer в master

Created by: Durman

Addressed problem description

Closes #4391 (closed)

I found that cleaning on blender exit does not have sense because these changes wont get into saved file. So the solution is to clean logs at file saving.

Preflight checklist

  • Code changes complete.