[gcmd-usr] advanced rename features

[Michael]

I'm using that heavily for so many years. But only today i recognized that you 
can pick one item of the preview list, and drag and drop it into another 
position ! Making it easy to sort things for a gallery or presentation.
Nice!

btw i'm also using the 'auto' setting for $c counter digits, but for better 
compatibility i need a minimum default of 2 instead of 1. That is, i don't use 
img-1 img-2 ... i need img-01 img-02 even for n<10. It should be just inserting 
one line after the calculation, but since i don't understand C it's impossible 
for me. Perhaps someone can tell me which line i had to insert and where...