Usage examples:
cp/mv/ln/etc file11.txt $(newname "/some/path/file11.txt")
cp/mv/ln/etc file11.txt $(newname "/some/path/whatever.txt")
If there's a file11.txt or whatever.txt already there, it will rename automatically to file11(1).txt or whatever(1).txt, and (N+1) from then on.
The whole path/name must be between quotes because of spaces and such things.
May be dangerous and somehow make you lose files...
