change item bullet by its level, not its bullet char

[c-alpha]

I am currently using - as the bullet character only.

Hence, list the current item replacement is visually not doing much for me. I am now toying with org-list-demote-modify-bullet to see whether I can get something along the lines of what I had in mind.

But I have a large legacy of Org files and data, that was authored with - list items only. Converting all that content does not look like an exercise that would seem particularly tempting to me.

I would thus like to propose an alternate mechanism for replacing list bullet symbols: by their level, i.e. the number of spaces preceding them. Determining the level may however not be trivial depending on the settings for the various org-indent-* stuff.

This new mode should again have two different behaviour options. Either repeatedly cycle through all defined list bullet symbols, or reuse the last one for all deeper levels.