New feature: provide granular means to configure warnings about items
that have been issued to a particular borrower before, according to
their checkout history.

- Global syspref ('CheckPrevCheckout'), set to 'hardno' by default,
  allows users to enable this feature library wide.
- Per patron category pref allows libraries to create overrides per
  category, falling back on the global setting by default.
- Per patron pref allows switching the functionality on at the level
  of patron. Fall-back to category settings by default.

* Koha/Patron (wantsCheckPrevCheckout, doCheckPrevCheckout): New
  methods.
* C4/Circulation.pm (CanBookBeIssued): Introduce CheckPrevCheckout
  check.
* admin/categories.pl: Pass along checkprevcheckout.
* koha-tmpl/intranet-tmpl/prog/en/modules/admin/categories.tt: Expose
  CheckPrevCheckout per category setting.
* koha-tmpl/intranet-tmpl/prog/en/modules/preferences/patrons.pref:
  Expose CheckPrevCheckout syspref.
* koha-tmpl/intranet-tmpl/prog/en/modules/members/memberentrygen.tt:
  Expose per patron CheckPrevCheckout preference.
* koha-tmpl/intranet-tmpl/prog/en/modules/members/moremember.tt: Expose
  per patron CheckPrevCheckout preference.
* koha-tmpl/intranet-tmpl/prog/en/modules/circ/circulation.tt: Add
  'CHECKPREVCHECKOUT' confirmation message.
* installer/data/mysql/kohastructure.sql: Modify structure of
  'categories', 'borrowers', 'oldborrowers'.
* installer/data/mysql/sysprefs.sql: Add 'CheckPrevCheckout'.
* installer/data/mysql/atomicupdate/checkPrevCheckout.sql: New file.
* t/db_dependent/Patron/CheckPrevCheckout.t: New file with unit tests.

Test plan:
- Apply patch.
- Run updatedatabase.
- Regenerate Koha Schema files.
- Run the unit tests.
- Verify 'CheckPrevCheckout' is visible in Patrons sysprefs and can be
  switched to 'hardyes', 'softyes', 'softno' and 'hardno'.
  + Check out previously checked out items to a patron, checking the
    message appears as expected.
- Verify no 'Check previous checkouts' setting appears on the borrower
  category pages if the syspref is set to a 'hard' option.
- Verify 'Check previous checkouts' setting appears on the borrower
  category pages and can be modified per borrower category.
  + Issue previously issued items to a borrower, checking the message
    appears as expected (This setting should override the default
    setting if that is set to a 'soft' option).
- Verify no 'Check previous checkouts' setting appears on the individual
  borrower pages if the syspref is set to a 'hard' option.
- Verify 'Check previous checkouts' setting appears on individual
  borrower pages and can be modified.
  + Issue previously issued items to a borrower, checking the message
    appears as expected (This setting should override the category
    setting and the default setting if the latter is set to a 'soft'
    option).

Followed test plan, works as expected.
Signed-off-by: Marc Véron <veron@veron.ch>

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>