Bug 36060: Simplify logic to enable/disable CheckinChecked/RenewChecked buttons

Bug 36060: Simplify logic to enable/disable CheckinChecked/RenewChecked buttons

This patch attempts to simplify for disabling/enabling the 'Check in selected items' and 'Renewal selected items' buttons.

To test:
1. APPLY patch, clear browser's cache
2. Have more than 1 checkout issued to a borrower.
3. Load the checkout table on circ/circulation.pl
4. Notice that there is now 'Renew selected items' and 'Checkin
   selected items' button.
5. Play around with each making sure that they work as excepted when
   checkouts are checked in either the 'Check in' or 'Renew' columns.
6. Uncheck everything in the 'Renew column', the 'Renew selected items'
   button should be disabled.
7. Uncheck everything in the 'Checkin column', the 'Checkin selected
   items' button should be disabled.
8. Try unchecking some of these to make sure the Renew/Checkin button is
   properly disabled when no related checkboxes are checked.
9. Try using the select all/none options at the top of both the 'Renew'
   and 'Checkin' columns. Make sure the 'Renew selected items' and
   'Checkin selected items' become properly disabled/enabled.
10. Make sure the 'Renew all' button still works properly.

11. Have two checkouts. Click one for Renew and one for Checkin. Click on Check in selected items.
12. When the table reloads the 'renew' selections should be retained
13. Have two checkouts. Click one for Renew and one for Checkin. Click on Renew selected items.
14. When the table reloads the 'check in' selections should be retained

15. Have overdues
16. Go to a patron account and load the issue table
17. The items that are overdue are checked for renewal by default
16. The 'Renew selected items' button show be enabled.

Signed-off-by: Brendan Lawlor <blawlor@clamsnet.org>
Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>