Email alerts to teachers

------------------------

Added a small new feature to the assignment module to alert teachers when
new emails come in.  This feature adds one new field (which is tested) but
the operation of the new code has not been tested yet at all (apart from
PHP syntax) and very likely has bugs in it.

I'm checking this in so I can do tests on test.moodle.com which has email
set up properly.

I'm off to bed right now but if anyone else wants to test this feature
before tomorrow please do!   :-)

While I'm rambling here in CVS, I need to have a good look soon at Pablo's work
on Assignment and see if I can merge it all in...

mod/assignment/db/postgres7.php

@@ -111,6 +111,10 @@ function assignment_upgrade($oldversion) {
         modify_database('','CREATE INDEX prefix_assignment_submissions_timemarked_idx ON prefix_assignment_submissions (timemarked);');
     }
 
+    if ($oldversion < 2005010500) { 
+        table_column('assignment', '', 'emailteachers', 'integer', '2', 'unsigned', 0, 'not null', 'resubmit');
+    }
+
     return true;
 }