[TYPO3-caretaker] Extensions Usage-Report anyone?

[Georg Kuehnberger]

Aloha! (spring is always so inspiring);

I've just asked myself whether you see an "inexpensive" way to generate 
an Extensions Usage-Report, which would report something like the following:
- EXTname, Version, List of Instances
- optionally including local/global/ext, activated/not.
- optionally total usage-count per EXT.

I recently did an easier one, reporting the T3-Core Version-Numbers 
grouped by Version, which was pretty easy to do given the latest results 
table.