If you type a group code of "Bedroom Furniture" then the group code should default to "bedroom-furniture" - with:
- all lower case letters
- spaces replaced by a -
- non-standard chars like "&" removed
- and no double dash as a result, ie. " & " (space, ampersand space) should leave "-" (single dash) not "--" or "---"
- obviously the result should be unique, if not suffix with -1 or -2 or whatever to get a unique code.
