Fixes for basket closing:

Fixes for basket closing:

 - I user has basket grouping permissions, don't display javascript popup for confirmation
 - if user has basket grouping permissions, after closing the basket redirect him to a page which asks which basketgroup to affect the basket to (with possibility to create a new basketgroup)
  - when done with this, redirect him to basketgrouping.pl to be able to print the basketgroup at once
 - factor out basket closing code from booksellers.pl (what was it doing there anyways?)