Restore the feature that multiple files with different extensions can be renamed without numbers

Review Request #111079 - Created June 17, 2013 and submitted - Latest diff uploaded

Frank Reininghaus
Actually, the idea of the "rename multiple files" feature is that the user provides a new name containing one or more '#'. The files are then renamed such that the '#' in the new name are replaced by numbers (1, 2, ... up to the number of renamed files), and the extensions are appended.

After I fixed it turned out that it was actually possible to rename multiple files with different extensions without providing numbers. The patch broke this because it enables the "rename" button if and only if there is a contiguous sequence of '#' characters and the length of that sequence is at least 1.

Even though this feature was sort of accidental, I think that there are valid use cases for it, and it doesn't really hurt anyone. So I propose to restore it and enable the button also if there is no '#' in the string, and all renamed files have different extensions.
Works for me, no regressions found so far.