Bug 25147: AllowSelfCheckReturns is in the wrong system preference section

Bug 25147: AllowSelfCheckReturns is in the wrong system preference section

This reverts commit 8aa9f2cc078932a0a4db434f8bd793de29a8ff7b.

I agree with the following comment and as such have reverted the patch.

Quoting Phil Ringnalda <phil@chetcolibrary.org>:

  Everything currently in the chunk labelled "Self Checkout" is
  preferences used to control sco-main.pl, a feature that does checkout
  and renewal, and optionally with the preference AllSelfCheckReturns,
  also checkin.

  Everything currently in the chunk labelled "Self check-in module" is
  preferences used to control sci-main.pl, a separate feature that does
  only checkin, and does checkin whether or not AllowSelfCheckReturns is
  set.

  I'd think a better solution would be to either rename the preference,
  which is actually AllowReturnsInSelfCheckout, or rename the chunks to
  make it more clear that they are preferences for two different features.

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>