Firstly, I'm replacing all use of old-style global variables like
$HTTY_REFERER with their new-style equivalent $_SERVER["HTTP_REFERER"]
Also using $_POST instead $HTTP_POST_VARS etc
Secondly, if gdversion == 0 (ie GD is not installed) then:
- users are not even allowed to upload new images
- graphs now just print a message instead of failing.
this allows Moodle to still be used even if GD is not present
Uploaded images are now saved even if the rest of the form
has errors.
If errors are found in the form then a message is printed up
the top to make it clearer that they need to fix something.
confirmation on deletions, removing deleted user from all student lists,
teacher lists and subscription lists and freeing up their username and
email to be used again.
there are three options:
0) Hide the email address from everyone (except the teacher of their course)
1) Allow everyone to see the email address, all the time.
2) Allow only participants in the same course to see the email address
Note, new field maildisplay in 'user'
