[r-t] delta based transposition for blue line generation

[Alan Burlison]

> Correct, but I think it's neater to deal with it there. It just needs to be
> a map from Char -> Option[Int]; a constant val better than a function in
> fact.

At present it's just a simple map:

  val placeToCCBR = "1234567890ETABCDFGHJKLMNPQRSUVWYZ".toSeq
  val CCBRToPlace = placeToCCBR.zipWithIndex.toMap

>> The other issue is that
>> it only really copes with the PN that's used on methods.ringing.org
>> and could do with extending to cope with other variants as well.
>
> I don't think you're far off that. The only thing you're obviously missing
> is the use of "x" for cross change, but that can easily be fixed in the
> CCBRToPlace map (if you collapse the special cases into there). Of course to
> deal with "full" place notations for symmetric leads you'll need some extra
> gubbins for the common & notation and other forms, but that to my mind sits
> outside of this bit of code.

Yeah, agreed.

-- 
Alan Burlison
--