GBE 1221: Make welcome letter faster and less wasteful

[bethlakshmi]

This report timed out on wdbfactional.

it will need a retest. Key elements:

• we only print the report if you’ve got a schedule. Ticket buyers only don’t get the report.
• refactored to use the scheduler roles function, which is more efficient
• put in a user-by-user function, and linked that to the manage profiles page, so that even if this doesn’t work on a live saver, registration can print one offs.
• when printing for the individual, ANY user will work, even if they have no schedule.

[bethlakshmi]

Also #1221 and #1222