enrol/authorize: Improve ssl check
enrol/authorize: improve layout and add missing fields from config
enrol/authorize: set default enrol email to users email
allow sender to be teacher or set in config
fix email and config settings
add replyto and proper config checks
set replyto correctly
add replyto to emails
enrol/authorize: Add new settings for enrolment expirations
enrol/authorize: add enrolment expiry support
enrol/authorize: remove unneeded config setting heading
enrol/authorize: improve email customisation settings
enrol/authorize: add enrolment period settings