Damyon Wiese authored May 16, 2014 and Marina Glancy committed Jun 23, 2014

(Only from webservices)

We were using ORDER BY id even though there was a perfectly good
attempt column to order the attempts by one user at one quiz.

Also, Oracle was complaining:
Debug info: ORA-01799: a column may not be outer-joined to a subquery

When different ID's are set for each sequence a number
of unit test failures appear.  They have been corrected
to allow unit tests to pass with the new generator in place.

This patch includes following fixes:
 - messages may be now sent when database transactions active
 - consistent return status on failure from message_send(), false is
   returned only when message not created in message(_read)? table,
   processor failure results in debugging message only and messages
   are not marked as read
 - message_sent is triggered always with id from message table
 - logic for marking messages as viewed was standardised
 - message_viewed event is triggered consistently
 - improved performance when fetching user preferences
 - full unit tests coverage for send_message() function
 - fixed multiple other smaller issues discovered by unit tests

Conflicts:
	theme/bootstrapbase/style/moodle.css

Call can_edit() instead of repeating a (slightly wrong) access check.