Bug 26577: Make basket.pl and cancelorder.pl use ->cancel

Bug 26577: Make basket.pl and cancelorder.pl use ->cancel

This patch makes the mentioned controller scripts use the new
$order->cancel method instead of DelOrder.

To test:
1. Apply this patches
2. Have a basket with some orders
3. Play with cancelling orders and removing baskets
=> SUCCESS: No behaviour change!
=> SUCCESS: No errors!
4. Sign off :-D

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>