Bug 18643: Remove dead code in reports/statistics 'Till reconciliation'

Bug 18643: Remove dead code in reports/statistics 'Till reconciliation'

File koha-tmpl/intranet-tmpl/prog/en/modules/reports/reports-home.tt contains a link to /cgi-bin/koha/reports/stats.screen.pl with label 'Till reconciliation' that is commented out since years.
Remove this link and the related files:
cgi-bin/koha/reports/stats.screen.pl
koha-tmpl/intranet-tmpl/prog/en/modules/reports/stats_screen.tt

To test:
- Apply patch
- Verify that Koha > Reports still display the same
- Verify that two files stats.screen.pl and stats_screen.tt are gone and thet they are not used
  anywhere in the Koha codebase

Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>