Minor Batch rename changes

[Maxence Bernard]

Hi Mariusz,
Just a quick note to let you know that I have reworked the dictionary
a bit and modified some of the Batch rename entries to factorize some
of them and removed some unused ones. Even though it is not currently
used, I left the "batch_rename_dialog.block_name" entry because I saw
you left some code corresponding to this feature.

The only visible change is the 'Digits' label, which I have renamed to
'Format' for more clarity. I hope you're OK with that.

Also, I got some feedback from our Dutch translator (Pieter) who had
trouble understanding what the 'Range' button does. I have to agree
that the dialog that gets popped up when clicking the "N[#-#] Range"
button is a bit hard to understand at first. Once you understand what
it does, it all becomes clear. May I suggest the following
modifications:
- change the dialog's title to "Range" (currently it is "Batch Rename")
- show the [N#-#] string corresponding to the current string selection

These are just suggestions, feel free to do whatever you please with
them :)

Cheers,
Maxence