Bug 7791: add ability to delete records when deleting a basket

Bug 7791: add ability to delete records when deleting a basket

Currently, when a basket is deleted, all the orders are deleted (there
is a foreign key in aqorders table on basketno).

This could be dangerous, and there is no warning.
After the deletion, unused biblios are left in the catalogue.

This patch
- adds a more detailed message describing the consequences of deletion
- give the choice of also deleting biblio records if possible

To test :
Test A :
1. create a basket with 4 orders:
- an order from a new record A
- an order from a record B which has already an item
- an order from a record C used in a subscription
- an order from a record D used in an other order
2. note the biblionumbers of the records used (or open them in other
   tabs in your browser)
3. click on "Delete basket"
4. choose button "Delete basket and orders"
5. check the catalogue : records A,B,C,D should still be there
Test B:
1. create a basket with 4 orders:
- an order from a new record A
- an order from a record B which has already an item
- an order from a record C used in a subscription
- an order from a record D used in an other order
2. note the biblionumbers of the records used (or open them in other
   tabs in your browser)
3. click on "Delete basket"
4. choose button "Delete basket, orders and records"
5. check the catalogue : records B,C,D should still be there. Record A
   should be deleted

Signed-off-by: Cedric Vita <cedric.vita@dracenie.com>
Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>