Bug 2093: Add OPAC Summary for logged-in users

Bug 2093: Add OPAC Summary for logged-in users

This patch adds a summary to the OPAC once the user has logged in that
shows the users number of checkouts, overdues, holds pending, holds
waiting and total fines. We also have a syspref OPACUserSummary to turn
this feature on and off. Default is ON.

To test:
1) Apply patch and update database
2) Set up some checkouts, overdues, holds pending AND waiting and fines
for a user
3) Log into OPAC as that user, see summary. Confirm links all work as
expected
4) Confirm that if there are no checkouts / overdues etc that the link
disappears from the summary
5) Turn OPACUserSummary OFF and confirm the summary does not show on the
mainpage.

Sponsored-by: Catalyst IT
Signed-off-by: Hugo Agud <hagud@orex.es>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>