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
Moodle tables.
ie user -> userid in many tables, plus in user_students
start -> starttime and end -> endtime
I've just done all this as carefully as I could ... I don't think
I missed anything but it's pretty intensive work and I'd be fooling myself
if I didn't think I'd missed a couple.
Note that this version should pretty much be able to bootstrap itself
using PostgreSQL now ... but this is untested
