Add auth_handle_institution_expiries, email site and institutional admins, suspend institutions if we are allowed to automatically do so.

Rename relevant elements from institutionexpiry... to institutionmembershipexpiry... to avoid naming clash.

(cherry picked from commit 30438e42)

Conflicts:

	htdocs/lib/version.php

(cherry picked from commit 236f761c)

Conflicts:

	htdocs/theme/default/templates/header.tpl

(cherry picked from commit a717e481)

(cherry picked from commit c2708a7f)

It was already the result of str_shorten, which means it wasn't vulnerable, but just to be sure.
(cherry picked from commit f06cc181)

(cherry picked from commit 7f10f82c)

(cherry picked from commit 3e40be79)

(cherry picked from commit a937ae52)

(#3185) Rename clam_scan_file -> mahara_clam_scan_file to prevent conflict with the PHP clamAV extension.