Add-In for Blender to automatically save files when rendering

Purpose
This Blender Add-On provides an easy way to document & preserve a project’s progress over time and to jump back to an arbitrary previous state, if required.
It saves the .blend, .png (render image, optional) and a readme.txt (optional infos) -file in a new, dedicated subdirectory on every rendering.
The new sub-directories are named YYMMDD-hhmmss + an optional short note, located in a base-directory of your choice.
Creating images/animations with Blender is usually a highly iterative trial-and-error process, that can lead into dead ends when using wrong techniques or taking bad artistic choices.
When trying to resume at a former version, it can be difficult to find the matching .blend file for that state of the project.
This add-on can be understood as